1 The plaintiff, a company incorporated in the United Kingdom, is part of the Element Six Group, which designs, develops and produces synthetic diamonds. In particular, the plaintiff specialises in the production of synthetic diamond material using chemical vapour deposition (“CVD”) techniques for technical applications in various industries, including optics, semiconductors and sensors. It is part of the De Beers Group, which is in turn a subsidiary of Anglo American PLC. The defendant, a company incorporated in Singapore, is a major manufacturer of CVD diamonds and has its diamond growing facility in Singapore. CVD refers to a process by which diamonds are grown from a substrate (ie, a diamond seed) by placing the substrate in a CVD reactor containing a mixture of gases and bombarding it with atoms. ¹

2 In this suit, the plaintiff contends that the defendant has infringed two of its patents registered in Singapore, Singapore Patent No 115872 (“SG 872”) and Singapore Patent No 110508 (“SG 508”). It relies on three samples of diamonds purchased, it contends, from the defendant or the defendant’s related entities or distributors. The defendant seeks to revoke the two patents. It also contends that the diamonds in question are not its responsibility and, in any event, do not infringe the patents.

3 SG 872 contains both product and process claims. The key product claim is Claim 1, which describes a CVD single crystal diamond material of a specified thickness of at least 0.5mm with certain characteristics. In particular, the diamond material has low optical birefringence, which is indicative of low strain, in the range of values stated in the claims (for convenience, I will refer to this range of values as the “SG 872 Range”). Birefringence refers to an optical property which is used to determine a diamond’s suitability for high-end optical applications. ²

4 The key process claim in SG 872 is Claim 62. It describes a method of producing the CVD diamond material which comprises, among other things, substrate preparation and the deliberate adding of nitrogen to the synthesis process. The level of nitrogen concentration (300ppb to 5ppm) is selected to be sufficient to prevent or reduce the formation of local strain generating defects, while also being low enough to prevent or reduce deleterious absorptions and crystal quality degradations. ³

5 SG 508 is a process claim in respect of the controlled conversion of a coloured single crystal CVD diamond to another colour under suitable and controlled heat treatment conditions, also referred to as annealing. The colours which may be produced include those in the pink-green range.

6 The plaintiff’s case on infringement is premised on three samples which were purchased by the plaintiff and/or its agents between 2014 and 2015, prior to the commencement of the suit on 12 January 2016 (“Sample 2”, “Sample 3”, and “Sample 4”, collectively the “Samples”). The Samples were purchased either from the defendant directly (in the case of Sample 4) or from entities that are allegedly related to the defendant (in the case of Samples 2 and 3).

(a) Sample 2 is an optical grade single crystal CVD diamond plate with product code “2PCVD303004N”. Sample 2 was purchased by Dr Andrey Jarmola on behalf of the plaintiff from Microwave Enterprises Ltd (“MWE”), under instructions from Dr Daniel James Twitchen on or around 12 May 2014. ⁴

(b) Sample 3 is a single crystal CVD diamond gemstone with product code “LG10225420”. Sample 3 was purchased by Dr Simon Lawson on behalf of the plaintiff from Pure Grown Diamonds Inc (“PGD”) on or around 27 October 2015. ⁵

(c) Sample 4 is an optical grade single crystal CVD diamond plate with product code “2PCVD505005N”. Sample 4 was purchased by Mr Pascal Pierra on behalf of the plaintiff directly from the defendant in Singapore in or around October 2015. ⁶

7 The defendant by counterclaim disputes the validity of SG 872 and SG 508 and seeks their revocation. In its defence, the defendant denies responsibility for the Samples and contends that, in any event, the Samples fail to show any infringement of the patents.

8 The case, therefore, may be analysed by reference to these issues:

(a) Validity of SG 872 and SG 508;

(b) Whether the defendants are responsible for the Samples; and

(c) Whether the Samples infringe SG 872 and SG 508.

9 As I explain below, I hold that SG 872 is valid, while SG 508 is not. Samples 2, 3 and 4 originate from the defendant, and infringe SG 872 but not SG 508.

10 As stated by the Court of Appeal in Mühlbauer AG v Manufacturing Integration Technology Ltd [2010] 2 SLR 724 (“Mühlbauer”) at [15], in order for an invention to be patentable, it must satisfy the three conditions set out in s 13(1) of the Patents Act (Cap 221, 2005 Rev Ed) (“Patents Act”). These are that:

(a) the invention is new (ie, the novelty requirement);

(b) it involves an inventive step (ie, the inventiveness or non-obviousness requirement); and

(c) it is capable of industrial application.

11 Requirement (c) is not in dispute in the present case for either of the patents.

12 Claim construction is integral to understanding whether claims are novel and inventive, and I therefore deal with this issue first. The claims of a patent provide the patentee with the monopoly which it is entitled to: First Currency Choice v Main-Line Corporate Holdings Ltd and another appeal [2008] 1 SLR(R) 335 (“First Currency Choice”) at [23]. In Lee Tat Cheng v Maka GPS Technologies Pte Ltd [2018] 1 SLR 856 (“Lee Tat Cheng”), the Court of Appeal reaffirmed the following key principles of claim construction at [41]:

13 The “notional skilled person” referred to by the Court of Appeal in Lee Tat Cheng is referred to by parties in this case, as is common, as a person skilled in the art (“PSA”).

14 In the present case the defendant’s PSA is a composite person having a Master’s degree in mechanical or chemical engineering and having a doctorate in applied physics, electrical engineering, optical engineering or a closely related field, aided by an engineer/technician with skills in mechanical polishing, laser cutting and correlated measurements. The plaintiff disputes this, and contends that the PSA is a team of people collectively having a Bachelor of Science in physics, chemistry or material sciences, and knowledge of diamond properties in all its forms at the material time (natural, high-pressure high-temperature (“HPHT”) and CVD diamonds) as well as working knowledge of CVD diamond synthesis and commercial production. ⁷ This disagreement has no practical significance, as no finding in the case turns upon this fine distinction. The present case would require consideration of a team of persons working in the field of growing CVD diamonds. In my judgment, the relevant PSA in such a field would include a team of individuals with expertise in diamonds and science generally, with access to individuals possessing doctorate qualifications. This is evidenced by the composition of the relevant teams on both sides in the present case. The plaintiff’s team included scientists such as Dr Phillip Martineau (who has a doctorate in solid state physics) ⁸ and Dr Geoffrey Scarsbrook (who has a doctorate in material physics). ⁹ As for the defendant, while the composition of its team is less clear, the defendant’s chief scientist, Dr Devi Misra, has a doctorate qualification as well. ¹⁰

15 For SG 872, arguments centred on Claim 1, a product claim, and Claim 62, a process claim. For SG 508, arguments focused on Claim 1. I deal with these in turn.

16 Claim 1 and in particular 1(ii) and 1(iii) are the focus of the dispute between parties: ¹¹

17 The plaintiff frames the inventive concept behind Claim 1 in SG 872 as follows: ¹²

18 The product in Claim 1 is for use primarily in optical applications. The utility of this invention is in its ability to create, on a commercial scale, diamonds for use in optical applications. These diamonds, having the properties those in the diamond trade term “Type IIa”, may also function as high quality gemstones. While natural diamonds could also be similarly used if they possessed the requisite properties, Dr Martineau explained that such natural diamonds are “a very uncertain supply” as natural diamonds with “particular properties” are required. ¹³

19 I deal first with the priority date of Claim 1. The plaintiff claims a priority date of 21 November 2002 for Claim 1 on the premise that, GB Patent Application No 0227261.5 (“GB 261”), its priority document, was filed on 21 November 2002. ¹⁴ While the defendant accepts that the priority date of Claim 1(ii) of SG 872 is 21 November 2002, it contends that the priority date of Claim 1(iii) is 20 November 2003, ¹⁵ because Claim 1(iii) is not supported by but extends beyond what is disclosed in GB 261.

20 The relevant provision is s 17(2) of the Patents Act:

21 The relevant principles on s 17(2) of the Patents Act, which is in pari materia with s 5(2) of the Patents Act 1977 (c 37) (UK), were set out by the English Court of Appeal in Unwired Planet International Ltd v Huawei Technologies Co Ltd and others [2017] Bus LR 1971 (“Unwired”) at [56]. The English Court of Appeal referred to the following “structured approach” in considering questions of entitlement to priority:

(a) First, to read and understand, through the eyes of the PSA, the disclosure of the priority document as a whole.

(b) Second, to determine the subject matter of the relevant claim.

(c) Third, to decide whether, as a matter of substance and not form, the subject matter of the claim can be derived directly and unambiguously from the disclosure of the priority document.

22 I summarise two further points made by the Court of Appeal at [71]–[72] relevant to this case:

(a) The assessment of priority is not done by asking whether everything which falls within the claim is clearly and unambiguously taught by the priority document. The exercise of determining priority involves asking whether the invention is directly and unambiguously derivable from the priority document, not whether every possible embodiment of the invention is so derivable.

(b) The priority document must be read with the benefit of the common general knowledge which forms the factual matrix against which the technical disclosure is assessed. Consequently, the disclosure may mean something different to a PSA who possesses the requisite knowledge than it does to someone reading the document without that knowledge. That observation is particularly relevant in a case where one is concerned not merely with what is made explicit by the document, but also with what is implicit in it, given that both explicit and implicit disclosure may be taken into account for priority.

23 The subject matter of Claim 1(ii) is a CVD diamond of low optical birefringence where mod sine delta does not exceed 0.9. The subject matter of Claim 1(iii) is a CVD diamond of low optical birefringence where the maximum value of delta n average does not exceed 1.5 x 10-4. According to the defendant’s expert, Dr Christoph Nebel, ¹⁶ the scope of the subject matter that is disclosed in GB 261 is limited by way of mod sine delta not exceeding 0.9. The material would only have a maximum phase shift of delta of 1.11998. The defendant rests on the assertion that the scope of Claim 1(iii) includes materials with the phase shift up to 1.571. In other words, the scope of Claim 1(iii) could include materials having 0.9 < mod sine delta < 1.

24 The plaintiff’s expert, Prof Mark Newton, explained in his AEIC that Dr Nebel had miscalculated the derivation of mod sine delta from delta n, as Dr Nebel had taken first order at π when first order ought to be π/2. On that premise, a delta n average value of 1.5 x 10-4 as specified in Claim 1(iii) converts at L (thickness) of 0.5mm and λ (wavelength) of 589.6nm to mod sine delta = 0.72. ¹⁷ The defendant emphasises that in cross-examination, Prof Newton accepted that Claim 1(iii) discloses a wider range of birefringence measurements compared to Claim 1(ii). However, whether or not Claim 1(iii) is broader than Claim 1(ii) is not relevant to the issue. Dr Newton explained that there is no 1:1 mapping between Claim 1(ii) and 1(iii) of SG 872. ¹⁸ The true question is whether the priority document, GB 261, directly and unambiguously conveys to the PSA an invention of sufficient breadth to encompass Claim 1(iii) of SG 872. I hold that it does. In this regard, the defendant does not contend that there is any difference in the inventive concept or the method between GB 261 and SG 872. Claims 1(ii) and 1(iii) are simply different ways of quantifying or measuring the optical birefringence of the CVD diamond produced through the process disclosed in GB 261 and SG 872, through the respective parameters. The defendant does not suggest that there is any difference in the process taught in GB 261 and SG 872, which is capable of giving rise to the claimed product in Claim 1. A low birefringent CVD diamond within the range claimed in Claim 1(iii) can therefore be derived directly and unambiguously from the priority document GB 261. There is implicit disclosure, and no difference in substance.

25 Accordingly, in my judgment, Claim 1(iii) is entitled to claim priority from GB 261, the operative date being 21 November 2002. This would also mean that the following pieces of prior art are not citable against SG 872: ¹⁹

(a) HP Godfried et al, “Diamond Solid Etalons for High-Stability DWDM Wavelength-Lockers” (“Godfried”), a conference paper presented in 2003.

(b) The plaintiff’s alleged prior sales of SG 872 diamonds on its website around September 2003.

(c) The material contained in Singapore Patent No 110506 (“SG 506”) which is not entitled to a priority date of 20 September 2002.

(d) The material contained in SG 508 which is not entitled to a priority date of 6 September 2002.

26 The applicable provision for the novelty requirement is s 14 of the Patents Act, which states:

27 There are two steps to the novelty inquiry. The first is to identify the prior art which are relevant to the invention in question. The second is to consider if the particular piece of prior art identified anticipates the invention. This is a question of fact. To anticipate the claim, the prior art must contain clear and unmistakeable directions to do what the patent claims to have invented. In Mühlbauer at [17], the Court of Appeal adopted the test for anticipation set out in the English Court of Appeal decision of The General Tire & Rubber Company v The Firestone Tyre and Rubber Company Limited [1972] RPC 457, stating:

28 The plaintiff contends that the prior art raised by the defendant do not plant the flag “at the precise destination” before the patentee. I briefly summarise the principles relevant in considering this issue.

29 First, the prior art must constitute an enabling disclosure. As the Court of Appeal explained in Genelabs Diagnostics Pte Ltd v Institut Pasteur and another [2000] 3 SLR(R) 530 at [24], “[t]he prior disclosure must not only identify the subject matter of the claim in the later patent, it must do so in a way that enables the [PSA] to make or obtain it, a kind of enabling disclosure” [emphasis added]. The concepts of disclosure and enablement must be kept distinct: Mühlbauer at [17]. Applying the principle of enabling disclosure to the present case, it is not sufficient for the defendant to disclose a low birefringent CVD diamond within the SG 872 Range in the prior art. That prior art must also enable the PSA to make or obtain the said CVD diamond.

30 Second, it is not necessary for the invention to be expressly disclosed in the prior art. Such disclosure can be implicit in that a PSA reading the prior art “must be taken to read documents in an intelligent way, seeking to find what is disclosed as a matter of substance”: Research in Motion v Inpro [2006] RPC 20 at [128] (see generally Terrell on the Law of Patents (Colin Birss gen ed) (Sweet & Maxwell, 18th Ed, 2016) (“Terrell”) at paras 11.68–11.71).

31 The disclosure can also be inherent. That is to say, if a PSA following the directions in the prior art will find that it inevitably results in the invention being made or done, the invention will not be novel. This is notwithstanding the fact that the prior art might not have described the invention in the same terms as the patent.

32 In the House of Lords decision of Merrell Dow Pharmaceuticals Inc v HN Norton & Co Ltd [1996] RPC 76 (“Merrell Dow”) at [44], Lord Hoffmann described this principle in the following terms: “if the recipe which inevitably produces the substance is part of the state of the art, so is the substance as made by that recipe”. Furthermore, “[w]hether or not a person is working a product invention is an objective fact independent of what he knows or thinks about what he is doing”: Merrell Dow at [47]. In Merrell Dow, Lord Hoffmann explained the principle with the following example at [36]. The Amazonian Indians have for centuries used a powdered tree bark to treat malaria. They were using quinine. Later, scientists discovered that the active ingredient within the tree bark was quinine. Could the scientists patent quinine, on the basis that they discovered this active ingredient which the Amazonian Indians had no knowledge about? The manufactured quinine could not be patented, on the premise that the teachings of traditional medicine contained sufficient information to extract the same product.

33 Third, the requirement of inevitability must be assessed in a practical manner. Neuberger J (as he then was), citing Fomento v Mentmore [1956] RPC 87 at 101 in Kirin-Amgen Inc v Roche Diagnostics GmbH [2002] RPC 1 at [702], observed that if the required result was obtained "save in exceptional circumstances (as one might say, 99 cases out of 100)" it would not deprive the earlier disclosure of its anticipating quality.

34 Fourth, the prior art must be considered separately when applying the test of anticipation. The court is not to combine or “mosaic” the disparate pieces of prior art: ASM Technology Singapore Pte Ltd v Towa Corp [2018] 1 SLR 211 (“ASM Technology”) at [59]. There is, however, a limited exception to the rule against “mosaicing”. Where an earlier document is referred to in a later document, it is possible to refer to the earlier document, but, even then, only to the extent of the specific portions referred to by the later document: Mühlbauer at [68].

35 Fifth, the prior art must be construed as if the court had to construe it at the date of publication, to the exclusion of information subsequently discovered by the PSA. An ex post facto analysis is not permissible: Mühlbauer at [18(a)]. In this connection, I should mention that while the plaintiff objects to the defendant’s use of publications post-dating the priority date for novelty, one ought to distinguish between the use of such publications to subjectively interpret the prior art and as a means to objectively establish a scientific fact. The former is impermissible given the rule against an ex post facto analysis. But there is nothing objectionable with using such publications as a means of proving a scientific fact. In Smith & Nephew Plc v Convatec Technologies Inc [2013] RPC 181, Birss J held that material post-dating the date of priority could be used to establish the solubility of a compound called AgCMC.

36 Sixth, as to the requirement that the prior art must have been “made available to the public”, this is satisfied even if the prior art was disclosed only to a single member of the public, unless such disclosure was given in confidence: Institut Pasteur and Another v Genelabs Diagnostics Pte Ltd and Another [2000] SGHC 53 (“Institut Pasteur”) at [188]. In addition, the requirement will still be satisfied even if no one has inspected the prior art: see Dien Ghin Electronic (S) Pte Ltd v Khek Tai Ting (trading as Soon Heng Digitax) [2011] 3 SLR 227 at [29]; First Currency Choice at [38], citing Aldous J (as he then was) in Lux Traffic Controls Limited v Pike Signals Limited [1993] RPC 107 at 133.

37 Finally, the burden of proving anticipation rests on the party resisting the patent claim: ASM Technology at [59].

38 In view of the breadth of prior art alleged, I sum up the allegations and main findings here.

39 The defendant made two contentions of a general nature. First, a prior art which discloses a natural or HPHT diamond within the SG 872 Range will anticipate Claim 1 as CVD diamonds are not a distinct type of diamond. I disagree and hold that CVD diamonds are a distinct type of diamond: see [44]–[54] below.

40 Second, the defendant contends the parameters of Claim 1 are arbitrary and meaningless. I hold otherwise. Nevertheless, that the birefringent parameters are meaningful and of technical significance does not mean that a prior art may not have anticipated SG 872. Lord Hoffmann’s reminder in Merrell Dow about quinine is apt here. The defendant seeks to otherwise show that the prior art is within the SG 872 Range of birefringence. On this issue, the mere fact that the prior art discloses and enables the production of a “low birefringent” CVD diamond does not, in and of itself, mean that Claim 1 is anticipated. Insofar as the defendant relies on prior art which discloses diamonds of “low birefringence”, qualitative terms such as “low birefringence” or its near cousin, “low strain”, should be treated with circumspection, in so far as there is no quantitative measurement involved. Dr Nebel himself expressed scepticism towards the use of qualitative terms, including with respect to birefringence. His evidence was that terms such as “high quality” could mean different things in different contexts, and was not sufficiently scientifically precise to function as a definition. ²⁰ I therefore do not consider that a mere enabling disclosure of a CVD diamond with “low birefringence” in the prior art will in and of itself anticipate SG 872, unless the defendant also proves that such a diamond will have a birefringence value within the SG 872 Range.

41 It should be noted that while Dr Nebel had cited an extensive list of prior art in his expert report, the defendant, in its closing submissions, focused in the main on two pieces of prior art, WO 01/96633 and WO 01/96634 (“WO 633” and “WO 634”) and SG 506. Given my observations at [39]–[40], the other pieces of prior art would in any event have been irrelevant. Thus, the defendant seeks to prove anticipation by these patents using the following three types of arguments for anticipation: ²¹

(a) The first argument relies on prior art that enables a PSA to make CVD diamond material with a certain dislocation density, Raman peak width and various electrical properties. The defendant asserts that there are certain correlations that can be observed between these properties and optical birefringence. For example, if the prior art would enable a PSA to make a CVD diamond of a certain dislocation density, and it is proven that the dislocation density results in a birefringence value that will fall within the SG 872 Range, the prior art will anticipate Claim 1 of SG 872. I organise these as Category (a) correlations below.

(b) The second argument relies on prior art which enables a PSA to make CVD diamond material suitable for applications such as etalons, anvils and diamond detectors. If the defendant can prove that such applications will have a birefringence value within the SG 872 Range, I accept that such prior art will anticipate Claim 1 of SG 872. I refer to these as Category (b) correlations below.

(c) Lastly, there is also a collection of prior art, referred to as Category (c) correlations below, where the defendant seeks to show that the Claim 1 product inevitably results from a similar method of teaching as SG 872.

42 Finally, I accept that it is not necessary for the defendant to conduct experiments to prove that the prior art anticipates SG 872. ²² Neither is the position being taken by the plaintiff, as clarified during oral closing submissions. ²³ As stated in SmithKline Beecham plc and others v Apotex Europe Ltd and others [2005] FSR 23 at [74], “a party attacking the validity of a patent is free to choose his weapons of attack to suit his own convenience, taking into account relevant considerations of cost and effectiveness”. Nevertheless, it still remains that the burden is on the defendant to prove anticipation. In the present case, the defendant could have proved anticipation by conducting experiments on the prior art to show that they would inevitably result in a CVD diamond of low birefringence within the SG 872 Range. There is no question that the defendant possesses the capabilities to carry out these experiments. As the defendant did not, it had to otherwise satisfy its burden of proof. I hold that it has not satisfied this burden of proof.

43 I turn then to the specific arguments summarised above.

44 A key plank of the defendant’s contentions on novelty rests on the premise that “[t]here is no difference between a CVD diamond, a mined diamond and a HPHT diamond”. ²⁴ According to the defendant, a CVD single crystal diamond material simply refers to a diamond that is grown by the process of CVD. CVD does not describe a property of the product. Therefore, for the purpose of novelty, any prior art which discloses a single crystal diamond of any origin (ie, mined, HPHT or CVD) with the same properties in SG 872 will invalidate SG 872. It is asserted that “a diamond is a diamond regardless of its origin”. ²⁵

45 In other words, the defendant construes Claim 1 of SG 872 as a product-by-process claim. Terrell at para 11–129 explains the key issue in such questions as follows:

46 The essential issue is whether the product, when produced by the process is itself a new, or unique, product. To make good their claim, the defendant has to show that a CVD diamond is exactly like a natural diamond in its various characteristics and properties.

47 In this regard, the defendant relies on the evidence of Mr Alexander Dean, who construed the phrase “CVD single crystal diamond” as follows: ²⁶

48 Mr Dean’s description does not answer the question. To say that the CVD process is not a physical feature of a diamond does not mean that the CVD process cannot give a diamond unique physical features that distinguish it as a product.

49 On the other hand, the plaintiff was able to demonstrate that a CVD diamond is distinguishable from natural and HPHT diamonds. ²⁷ Prof Newton explained that the distribution of defects in the three forms of diamond are different as a result of their different growth conditions. ²⁸

50 For instance, the distribution of nitrogen defects are different: ²⁹

51 Another example of the differences between the three types of diamond is their distribution of dislocations. Dislocations are linear defects which typically extend to the external surfaces of a single crystal. ³⁰ Prof Newton explained: ³¹

52 In cross-examination, Dr Nebel agreed, in the main, with Prof Newton’s explanation of the difference in distribution of dislocations in CVD and HPHT diamonds (and offered no comment on natural diamonds). Although he introduced a qualification in respect of CVD diamonds, he did not dispute the substance of Prof Newton’s explanation concerning the distribution of dislocations: ³²

53 In this connection, the defendant points out that Prof Newton agreed that the defects in CVD diamonds can also be found in natural and HPHT diamonds. ³³ Dr Newton “could not point to any defect that exists only in CVD diamond and no other diamond”. ³⁴ Even if there is a difference in the distribution of defects in CVD diamonds, the plaintiff has not shown that this will cause CVD diamonds to possess a unique property that other types of diamonds do not possess. ³⁵ Further, if defects in a diamond are distributed homogeneously, the resulting material will have low birefringence regardless of its origin and could be used for optical applications. ³⁶ The diamond will not perform any differently depending on its origin. ³⁷

54 These points again do not answer the question. It is clear that a CVD diamond is a distinct type of diamond as the distribution, nature and combination of defects differ among the three types of diamonds. Arising from these differences, a PSA will be able to identify the type of diamond through instruments such as DiamondView or a photoluminescence spectrometer. ³⁸ Indeed, the defendant’s expert Dr Filip De Weerdt accepted in cross-examination that the DiamondView instrument was a “reliable test” for identifying CVD diamonds: ³⁹

55 A parametritic claim is one where the claim is defined by “technically meaningless” and “arbitrary” parameters (see Raychem Corp’s Patents [1998] RPC 31 (“Raychem”) at 47). The defendant contends that SG 872 is one such claim.

56 As explained by Laddie J in Raychem at 37, parametritis does not constitute an independent ground for invalidating a patent. The task of the court remains the same, which is to ascertain whether there has been anticipation.

57 The defendant’s contention that the parameters in Claim 1(ii) and Claim 1(iii) are technically meaningless and arbitrary is unmeritorious. In fact, the parameters in Claims 1(ii) and Claims 1(iii) are essential insofar as they provide a quantitative measurement of the birefringence in the diamond material. As Prof Newton explained, it was with such measurements that the suitability of the diamond for optical applications could be determined by the end user. ⁴⁰

58 Accepting for present purposes the plaintiff’s position that the CVD diamond material in SG 872 is of lower birefringence than that produced previously, it would have been logical and sensible to define that birefringence in the quantitative terms specified in Claims 1(ii) and 1(iii). ⁴¹ As of 21 November 2002 (ie, the priority date of SG 872), those parameters could be measured using a system known as the Metripol (previously known as the Deltascan), which was developed by Dr Anthony Michael Glazer (the plaintiff’s expert), Dr Werner Kaminsky (the defendant’s expert) and Dr Morten Geday (the defendant’s witness) in or around 1995.

59 In this regard, while the experts are in agreement that cross-polar imaging could be used to assess birefringence, the images would only have provided a “qualitative assessment” of birefringence, rather than a “quantitative measure”. The cross-polarised images would thus not have been a substitute for the Metripol and the parameters in Claims 1(ii) and 1(iii) of SG 872. Dr Kaminsky said as follows: ⁴²

60 In other words, cross-polar images are able to provide an estimate of the birefringence in the CVD diamond. Essentially, a PSA can compare the colours in a cross-polar image with a chart known as the Michel-Levy chart to obtain an estimate of birefringence. However, the Metripol furnishes a quantitative measurement with precision. It is not dependent upon the perception of the user. It is useful, and therefore is not technically meaningless.

61 The other aspect of the defendant’s contention that SG 872 is a parametritic claim is the alleged inaccessibility of the Metripol as of 21 November 2002, the priority date of SG 872. Dr Geday’s evidence was that before 2004, there were fewer than eight units of the Metripol sold. ⁴³ The defendant therefore contends that the Metripol was a “rare and inaccessible apparatus”. ⁴⁴ This contention ignores the fact that the SG 872 patent itself referred to the Metripol (under its previous name Deltascan) and Oxford Cryosystems, the supplier of the Metripol. A PSA reading the patent would thus know where and how to obtain the Metripol and there is nothing to suggest that the Metripol was not for sale. Dr Glazer’s evidence was that around 30 units of the Metripol were sold. ⁴⁵ Even if one were to take the defendant’s case at its highest (ie, that there were fewer than eight units sold), the fact that these units were sold shows that the Metripol was certainly available for the PSA to obtain. Dr Geday and Dr Kaminsky confirmed this in cross-examination. ⁴⁶

62 For completeness, I note that there were also similar instruments to the Metripol which could be used to measure birefringence as of the priority date, such as the Polscope, although both Dr Glazer and Dr Geday considered that instrument to be “inferior in terms of precision”. ⁴⁷ SG 872 does not mandate the use of the Metripol to measure birefringence and there is no evidence to suggest that these alternative instruments were not accessible.

63 I turn then to consider whether WO 633/634 has birefringence within the SG 872 Range.

64 WO 633 and WO 634 are patents owned by the plaintiff which claim an “electronic grade” CVD diamond. It is accepted by the experts from both parties that the processes in WO 633 and WO 634 are, for the purposes of this suit, the same. In both patents, the PSA is taught to eliminate nitrogen in the synthesis gas phase. ⁴⁸ There is no dispute that both patents are citable against SG 872 as prior art. As highlighted above, WO 633 and 634 does not provide a quantitative measurement of the birefringence of the CVD diamond material produced. Nevertheless, the defendant’s position is that such diamond material will be of low birefringence within the SG 872 Range.

65 For Category (a) correlations, some care must be taken to identify whether the authors of that prior art were seeking to establish a certain correlation between, for example, dislocation density and birefringence, or whether those were just empirical observations based on a limited set of data. In this regard, continuing with the example of dislocation density, I accept that the defendant does not need to prove a precise mathematical correlation between dislocation density and birefringence. ⁴⁹ In other words, it is not necessary to show a known formula to convert dislocation density into a corresponding value of optical birefringence. It will suffice, for instance, if the defendant can show, as it contends, that CVD diamonds with a dislocation density of less than 100/mm2 will have a birefringence of less than 10-4, which is within the SG 872 Range.

66 I deal with this correlation first as it is the premise for several of the other correlations discussed below.

67 Dr Nebel relies on various publications to prove the alleged correlation between dislocation density and birefringence. According to Dr Nebel, diamonds with a dislocation density of less than 100/mm2 will have a birefringence of less than 10-4. Diamonds with a dislocation density of less than 10/mm2 will also have a birefringence of less than 5 x 10-5. ⁵⁰ Both of these birefringence values fall within the SG 872 Range.

68 In Arthur Ruoff et al, “Synthetic diamonds produce pressure of 125 GPa (1.25 Mbar)” (1987) 2(5) J Mater Res 614 (“Ruoff 1987”) ⁵¹ at p 617, the authors stated that:

69 However, as the plaintiff points out, there are several difficulties with Dr Nebel’s reliance on Ruoff 1987 to prove the alleged correlation between dislocation density and birefringence.

70 First, Ruoff 1987 concerned HPHT diamonds and not CVD diamonds. It does not establish that a CVD diamond with a dislocation density of less than 100/mm2 will have a birefringence of less than 10-4. This is a material difference. This is because, as Prof Newton explained, and I have dealt with this at [51], the birefringence of a diamond material is affected not just by its dislocation density, but also by the distribution and direction of propagation of those dislocations, which may vary between the different types of diamond.

71 Prof Newton’s evidence is also that one cannot derive the optical birefringence of a CVD diamond from its dislocation density: ⁵²

72 In cross-examination, Dr Nebel disagreed that “the three materials [ie, natural, HPHT and CVD diamonds] have very different distributions of dislocations”. ⁵³ However, Dr Nebel did not disagree that the birefringence of a diamond material is affected not just by its dislocation density, but also by the distribution and direction of propagation of those dislocations, which he agreed (in the main) could vary among the different types of diamonds: see [52] above.

73 In any event, the alleged correlation was also expressed in equivocal terms: the authors had only stated that the dislocation density of the HPHT diamonds in their experiment was “likely” to be less than 100/mm2. It does not appear that the authors in Ruoff 1987 were seeking to establish the precise nature of the correlation between optical birefringence and dislocation density. They were merely seeking to report their empirical findings on the optical birefringence and dislocation density of the HPHT diamonds they had grown. Further, there is no mention of the thickness of the diamonds in Ruoff 1987, and in particular, whether they were at least 0.5mm (which Claim 1 of SG 872 requires). ⁵⁴ As stated in SG 872 itself, “dislocations can slowly multiply during growth” (increasing thickness), which will therefore also increase birefringence. ⁵⁵

74 These objections to Ruoff 1987 apply equally to the other publications that Dr Nebel relied on, which I discuss briefly.

75 In N V Surovtsev and I N Kupriyanov, “Temperature dependence of the Raman line width in diamond: Revisited” (2015) 46 J Raman Spectrosc 171 (“Surovtsev 2015”) ⁵⁶ the authors state that HPHT diamonds were used in the study and the average value of the birefringence was estimated to be less than 5 x 10-5 and the dislocation density found to be within 1-10/mm2. The study was not conducted on CVD diamonds and there is nothing to suggest that the authors were seeking to establish a wider correlation between optical birefringence and dislocation density.

76 In Yoshiaki Mokuno et al, “A nitrogen doped low-dislocation density free-standing single crystal diamond plate fabricated by a lift-off process” (2014) 104 Appl Phys Lett 252109 (“Mokuno 2014”), ⁵⁷ a nitrogen-doped single crystal diamond plate was fabricated by CVD from a HPHT synthetic type IIa seed substrate. The resulting diamond plate had a dislocation density of 4/mm2 and an average birefringence of less than 3 x 10-5. The diamond in Mokuno 2014 was CVD diamond. However, the authors were merely reporting the dislocation density and birefringence of the one particular diamond plate which they had fabricated, rather than seeking to suggest any wider correlation.

77 Whilst the above deals with WO 633/634, the argument made by the defendant in the context of SG 506, which refers to a CVD diamond with dislocation density of less than 100/mm2, fails for the same reasons.

78 Next, the defendant highlights that the correlation between breakdown electric field and optical birefringence shows that WO 633 and WO 634 anticipate Claim 1 of SG 872. ⁵⁸

79 Example 3 of WO 634 discloses a CVD diamond with a breakdown electric field of 100 V/μm. According to Dr Nebel, the “significantly good breakdown voltage … indicates that this diamond would have low dislocation density and therefore low birefringence [less than 10-4]”. ⁵⁹ In the same vein, WO 634 discloses CVD diamond material with breakdown electric fields larger than 45 V/μm. ⁶⁰

80 To prove the correlation between breakdown electric field and optical birefringence, the defendant relies on Michal Pomorski, “Electronic Properties of Single Crystal CVD Diamond and its Suitability for Particle Detection in Hadron Physics Experiments” (2008) (“Pomorski 2008”) which concerned a study on single crystal diamond material supplied by the plaintiff, “grown with the microwave assisted CVD technique on <1 0 0> oriented high-pressure high-temperature (HPHT) diamond substrates”. ⁶¹ More than 30 samples of various thicknesses (50 to 500μm), sizes (3 x 3 to 5 x 5mm2) and surface preparations were tested with respect to their “detector properties” and their results compiled. The birefringence of the samples was assessed using cross-polar imaging. ⁶² For a sample which had a breakdown electric field of 0.1 V/μm (BDS11), the cross-polar images appeared as bright areas, indicating high birefringence. For a sample which broke down at fields larger than 3 V/μm (SC13BP), the cross-polar images were dark, indicating that there was no strain and hence low birefringence. ⁶³

81 Accordingly, the defendant’s position is that diamonds with a breakdown electric field of more than 3 V/μm will have a birefringence of less than 10-4, which is within the SG 872 Range. The diamond material in WO 633/634 would all have breakdown electric fields larger than 3 V/μm.

82 However, Prof Newton highlights certain difficulties with the alleged correlation between breakdown electric field and birefringence. First, in so far as that correlation is premised on identifying a correlation between breakdown electric field and dislocation density, followed by dislocation density and birefringence, the difficulties in identifying the correlation between dislocation density and birefringence have been discussed above.

83 Further, in Pomorski 2008, the author had used 30 samples which were 50 to 500μm thick. The only sample for which an explicit thickness was given was 400μm thick. However, SG 872 requires the diamond material to be at least 0.5mm thick (ie, at least 500μm). Furthermore, it also appears that the areas which were tested in Pomorski 2008 were less than 1.3 x 1.3 mm in area, which is required by SG 872. ⁶⁴

84 I had earlier addressed the alleged correlation between dislocation density and birefringence. In his presentation to the court, Dr Nebel also explained that from the dislocation density, one could derive the strain (measured by what is known as Raman Full width at half maximum (“FWHM”)) and in turn derive the birefringence. WO 633 and WO 634 disclose a CVD diamond of a low Raman FWHM of 1.52cm-1 and 1.54cm-1. According to Dr Nebel, the typical Raman FWHM of a high quality diamond with near-perfect lattice is around 1.5cm-1. Relying on various publications, Dr Nebel contends that diamonds with Raman FWHM of less than 1.6cm-1 will have birefringence of less than 3 x 10-5, which is at least five times less than the maximum birefringence claimed in SG 872.

85 To prove the alleged correlation between Raman FWHM and birefringence, the defendant relies on the following publications.

86 In the supplementary materials for Surovtsev 2015 (“Surovtsev 2015S”), ⁶⁵ it is reported that a given sample in the study had a Raman FWHM of 1.53cm-1 and average birefringence of about 3±1 x 10-5. However, as pointed out by Prof Newton, Surovtsev 2015S concerned work on HPHT diamonds as opposed to CVD diamonds. The same difficulties with using HPHT diamonds to prove the alleged correlation between dislocation densities and birefringence for CVD diamonds would apply here. Further, Surovtsev 2015S only concerned empirical observations of Raman FWHM and average birefringence, and did not seek to establish the proposition that a Raman FWHM of 1.53cm-1 would result in birefringence in the 10-5 range. ⁶⁶

87 H Sumiya, N Toda & S Satoh, “Mechanical properties of synthetic type IIa diamond crystal” (1997) 6 Diamond and Related Materials 1841 (“Sumiya 1997”) concerned work on HPHT and natural diamonds as opposed to CVD diamonds. Moreover, it is unclear how Dr Nebel manages to establish a correlation between optical birefringence and Raman FWHM when Sumiya 1997 does not contain any discussion of the concept of birefringence, let alone the birefringence values of the diamonds in the experiment conducted by the authors.

88 Alexandre Crisci et al, “Residual strain around grown-in defects in CVD diamond single crystals: A 2D and 3D Raman imaging study” (2011) 208(9) Phys Status Solidi A 2038 (“Crisci 2011”) ⁶⁷ was a study reporting the results of Raman imaging investigation of defects in single crystal CVD diamonds.

89 In cross-examination, Dr Nebel agreed with Prof Newton that the focus of Crisci 2011 was on the effect of five particular defects in the diamond (representing about 1.2% of the total surface area of the sample), rather than its dislocation density. ⁶⁸ The correlation which Dr Nebel sought to draw was that from the dislocation density of the diamond, one could derive strain (measured in Raman FWHM) which was in turn indicative of birefringence. Crisci 2011 therefore does not support the correlation which the defendant seeks to draw.

90 Daniel Howell et al, “Inclusions under remnant pressure in diamond: a multi-technique approach” (2012) 24 Eur J Mineral 563 (“Howell 2012”) is concerned with natural diamonds and not CVD diamonds. Further, in so far as Howell 2012 used the Metripol to measure the birefringence of the samples, that to some extent supports the plaintiff’s position that one cannot rely on dislocation density and Raman FWHM (among others) to determine whether the birefringence of a CVD diamond falls within a given range.

91 WO 633 and WO 634 disclose a diamond with a charge collection efficiency (“CCE”) of more than 96%. According to the defendant, diamonds with a CCE of more than 90% will have low dislocation density and therefore a birefringence of less than 1.5 x 10-4. Dr Nebel relies on A Lohstroh et al, “Effect of dislocations on charge carrier mobility – lifetime product in synthetic single crystal diamond” (2007) 90 Appl Phys Lett 102111 (“Lohstroh 2007”) for the proposition that the presence of dislocations reduces the CCE of a given sample. Lohstroh 2007 contains no discussion of the birefringence of the diamond, and Dr Nebel explained in cross-examination that the correlation between CCE and birefringence was premised on the relationship between dislocation density and birefringence. The difficulties associated with that latter correlation have already been explained above.

92 The defendant also contends that WO 633/634 anticipates Claim 1 of SG 872 as it is explicitly mentioned that the diamond material is suitable for use in anvils and diamond detectors. The defendant asserts that anvils and detectors are of low birefringence falling within the SG 872 Range. While there is no mention of etalons in WO 633/634, the defendant relies on Godfried and Whitehead 2003 to prove that the diamond material in WO 633/634 was suitable for use as etalons as well. These arguments are related to that concerning SG 506, where the defendant relies on the reference to etalons in SG 506 to prove that it anticipated Claim 1 of SG 872.

93 The plaintiff argues that the prior art was concerned with electronic grade CVD diamonds rather than optical grade CVD diamonds. ⁶⁹ The electronic grade single crystal diamond had minimal nitrogen content and thus possessed good charge carrier mobilities, making it suitable for electronic applications. The plaintiff contends that such electronic grade CVD diamonds gave rise to a relatively high level of birefringence. This was explained in the patent as follows (see in particular the sentence highlighted in emphasis): ⁷⁰

94  It was Dr Scarsbrook’s evidence that the electronic grade material in WO 633 and WO 634 was of comparatively lower birefringence than the preceding material, but was still not suitable for the “optical market”: ⁷¹

95 As Prof Newton explained in cross examination: ⁷²

96 Dr Philippe Bergonzo, who gave expert evidence on behalf of the plaintiff, provided a similar account: ⁷³

97 Dr Scarsbrook, Prof Newton and Dr Bergonzo’s evidence that the electronic grade material in WO 633 and WO 634 had a higher birefringence than the SG 872 Range is, to some extent, supported by sample 4 of Example 9 in SG 872 (although I note that there is no quantitative measurement of birefringence, as opposed to scatter, in Example 9). A set of five samples was measured for scatter, indicative of strain which is in turn indicative of birefringence. The first three samples were made using the method in SG 872, while the fourth sample was made using the method in WO 633/634 (ie, where nitrogen was below 300 ppb). The result, as stated in the patent, was as follows: ⁷⁴

98 Indeed, in its written submissions, the defendant acknowledged that SG 872 itself discloses that the controlled addition of low levels of nitrogen will reduce the birefringence of CVD diamonds. ⁷⁵ It suffices to note at this point that the defendant could have performed experiments to prove that the controlled addition of low levels of nitrogen will not reduce birefringence in CVD diamonds, but did not do so. The burden is on the defendant to prove that the patent is not novel or lacks inventiveness: ASM Technology at [59] and [78].

99 Instead of the controlled addition of low levels of nitrogen, WO 633 and WO 634 teach the removal of nitrogen in the synthesis gas phase. There is therefore no overlap in the range of nitrogen concentration between WO 633/634 and SG 872. At p 18 of WO 633, it is states as follows: ⁷⁶

100 This distinction is summed up by Prof Newton’s explanation: ⁷⁷

101 This explanation, nevertheless, does not go to the heart of the inquiry, which is the claim that is asserted by Claim 1. This is the birefringence within the SG 872 Range. While, depending on the quality of the substrate, the teaching in SG 872 may allow a PSA to attain lower levels of birefringence, the birefringence claimed in Claim 1 is for a specific range, intended for optical instruments. On this issue, the plaintiff’s label for WO 633/634, “electronic grade”, does not further the analysis, because there is no range specified for electronic grade diamond. Anvils and etalons are, in any event, optical instruments. Therefore it is important to examine the defendant’s assertions that the teachings in WO 633/634 and SG 506 allowed and provided for the production of anvils, detectors and etalons in the SG 872 Range of birefringence.

102 In the “Summary of the Invention” for WO 633, it is stated that: ⁷⁸

103 The defendant, relying on Dr Nebel’s evidence, contends that the diamond in WO 633 can be used for diamond detectors, which “must have a birefringence of less than 10-4”. ⁷⁹ In support of this contention, the defendant relies on the following publications: US 932; E A Burgemeister, “Dosimetry with a diamond operating as a resistor” (1981) 26(2) Phys Med Biol 269 (“Burgemeister 1981”); D R Kania et al, “Diamond radiation detectors” (1993) 2 Diamond and Related Materials 1012 (“Kania 1993”); A M Zaitsev, Optical Properties of Diamond: a Data Handbook (Springer, 2001) (“Zaitsev”); Grzegorz Kowalski et al, “Synchrotron X-ray studies of strain in (100)-oriented high pressure-high temperature (HP-HT) synthetic diamonds” (1996) 5 Diamond and Related Materials 1254 (“Kowalski 1995”);”); Pomorski 2008; and G P Freeman et al, “Differences between counting and non-counting diamonds – Part II: birefringency and luminescence” (1952) 18(1) Physica 9 (“Freeman”).”).

104 It ought to be emphasised that what the defendant must show is that for a CVD diamond to be used as a diamond detector (as opposed to a natural or HPHT diamond), it must have a birefringence within the SG 872 Range. On that basis, the only publications that are potentially relevant are US 932, Burgemeister 1981 and Freeman. The other publications, at their highest, only go towards showing that for a CVD diamond to be used as a diamond detector, it should ideally be of low birefringence, which Dr Scarsbrook accepted was a “good way of pre-selecting [diamonds suitable for use as detectors]”. ⁸⁰ However, the precise range is not quantified:

(a) Kania 1993: “[T]ype IIa, low birefringence diamonds are best for radiation detectors. ⁸¹

(b) Zaitsev: “The birefringence effect can also be used for the selection of diamonds suitable for fabrication of radiation detectors.” ⁸²

(c) Kowalski 1995: “The presence of any source of strain would affect the performance of diamond in electronic applications (radiation detectors).”

(d) Pomorski 2008: “Cross-polarised light microscopy is a fast technique allowing a pre-selection of diamond samples of superior quality, which is helpful for detector development.”

105 I turn then to US 932, which relates to a method for the detection of ionising radiation by means of a diamond detector, and the construction of the said diamond detector using HPHT diamonds. ⁸³ The defendant contends that it supports its argument that diamond detectors must have a low birefringence of less than 10-4. Since the diamond in WO 633 is suitable for use as detectors, it would thus appear that the diamond produced in WO 633 would also be of low birefringence.

106 The relevant extracts in US 932 read:

107 However, US 932 relates to HPHT diamonds. It claims that for HPHT diamonds, a certain concentration of nitrogen, together with a stated birefringence, allows HPHT diamonds to be used as detectors. There is nothing to suggest that the CVD diamond in WO 633, which has a different nitrogen concentration, would have the same low birefringence of less than 10- 4, notwithstanding that it was suitable to be used for diamond detectors. ⁸⁴ Prof Newton explained as follows:

108 Therefore, while birefringence is a measure that applies uniformly across all kinds of diamonds, a HPHT diamond’s use as a detector is not solely dependent on its birefringent values, but also on other factors such as the distribution of nitrogen in the diamond. This nitrogen structure is different in the CVD diamonds produced from WO 633/634: as Prof Newton stated, “[i]n US 932, the level of nitrogen permitted in the diamond solid is orders of magnitude greater than that in the CVD diamond of WO 633”. The correlation between the birefringence values of the WO 633/634 diamond and the US 932 diamond has not been established, despite their both functioning as detectors. Dr Nebel had no response to this.

109 Dr Nebel also referred to Burgemeister 1981 and Freeman, which go towards showing that in order for a natural diamond to be used for detectors, it ought to have birefringence of less than 10-4. ⁸⁵

(a) In Burgemeister 1981, it was stated that counting diamonds (ie, detectors) should be colourless, of type IIa and show little birefringence. Several thousand natural diamonds were preselected based on these criteria, and eventually, it was found that one of them was able to operate as a detector – a colourless type IIa diamond with little birefringence less than 10-4. However, as observed by Prof Newton, Burgemeister 1981 merely reports that a natural diamond of birefringence less than 10-4 was suitable for use as a detector. There was no reference to CVD diamonds at all.

(b) In Freeman, it was observed that the “order of birefringency” of counting diamonds is always corresponding to circa 1000 Å, for 1mm thickness of the crystal, corresponding with changes in the refractive index of the order of 10-4. However, Freeman was concerned solely with natural diamonds and not CVD diamonds.

110 These articles, concerned with natural diamonds selected for use in detectors, are irrelevant to the discussion. All they show is that low birefringent material make good detectors, rather than illustrating, as required, that all detectors are low birefringent.

111  The diamond in WO 634 is said to be “suitable for use as diamond anvils in high pressure experiments and manufacture”. ⁸⁶ Likewise, Dr Scarsbrook stated during the expert panel that the diamond in WO 633 was also able to be used for anvils. ⁸⁷ It is not disputed that anvils have low birefringence and both Dr Scarsbrook and Dr Bergonzo acknowledged this. ⁸⁸

112 What is in contention is whether CVD diamond anvils must have a birefringence of less than 10-4, as the defendant claims. If so, the birefringence of the CVD diamond in WO 633/634 must fall within the SG 872 Range.

113 The various publications are as follows.

114 In Michael Seal, “Diamond Anvils” (1984) 16 High Temperatures-High Pressures 573 (“Seal 1984”),”), it is stated that “[t]he most commonly specified material parameter for the diamond is ‘low birefringence’ … it is possible to select diamonds with values as low as 0.00005 [ie, less than 1.5 x 10-4].” In similar vein, Michael Seal, “Diamond Anvil Technology” in M H Manghnoni, High-Pressure Research in Mineral Physics (M H Manghnoni & Y Syono eds) (1987) (“Seal 1987”) states that:

115 Both Seal 1984 and Seal 1987, however, deal with natural diamonds and in any event merely specify the “common practice”. It is not stated that CVD diamonds outside the SG 872 Range cannot be used as anvils.

116 In Yogesh K Vohra & Suresh S Vagarali, “Isotopically pure diamond anvil for ultrahigh pressure research” (1992) 61 Appl Phys Lett 61 (“Vohra 1992”),”), it is said that “[i]n few specialized applications, like high pressure research using diamond anvil cell devices, natural diamond crystals with low intrinsic strain and strain birefringence lower than 10-4 are usually employed.” ⁸⁹ Vohra 1992, however, relates to natural diamonds and in any event, merely states that natural diamonds of birefringence lower than 10-4 are “usually employed”.

117 In Ruoff 1987, the authors said that:

Similarly, in Arthur L Ruoff & Yogesh K Vohra, “Multimegabar pressures using synthetic diamond anvils” (1989) 55 Appl Phys Lett 232 (“Ruoff 1989”), the authors stated that:

118 Ruoff 1987 and Ruoff 1989 are concerned, however, with HPHT diamonds instead of CVD diamonds. In any event, they merely state that low birefringent diamonds were used for experiments/studies and do not go further to establish that diamond anvils must be within the SG 872 Range.

119 The defendant also relies on a certain extract from the plaintiff’s website dated 18 September 2003 to contend that diamond anvils must have a birefringence of less than 10-4. However, the extract relied upon does not show that diamond anvils must have a birefringence of less than 10-4. ⁹⁰ It merely states that “specially selected anvils … with low … birefringence” are available for sale, and matched to specifications (normally < 0.0001 or < 0.00005) [emphasis added in italics and bold italics].

120 It is claimed that the material in WO 633 and WO 634, apart from being suitable for use as detectors and anvils, was also suitable for use as etalons, which is said to fall within the SG 872 Range.

121 In making this argument, the defendant relies on Godfried, a conference paper presented in September 2003. It post-dates the priority date of SG 872 and is not citable as prior art.

122 However, Godfried, in stating that the authors “have developed solid etalons made from synthetic single-crystal CVD diamond” [emphasis added], cites Jan Isberg et al, “High Carrier Mobility in Single-Crystal Plasma-Deposited Diamond” (2002) 297(5587) Science 1670 (“Isberg”), which referred to the process in WO 633/634. Isberg makes no reference to etalons. However, the defendant contends that the citation of Isberg in Godfried shows that the electronic grade diamonds produced using the method disclosed in Isberg (ie, WO 633/634) could be used as etalons and were of low birefringence within the SG 872 Range.

123 I reject the defendant’s contention. Godfried was vetted by the plaintiff. I accept the plaintiff’s explanation that the diamond material referred to in Isberg was not the same as that in Godfried. The reference to Isberg in Godfried was necessary so as to provide an example of single crystal CVD diamond material. In this regard, the plaintiff relies on the evidence of Dr Scarsbrook, who was part of the vetting circle in the plaintiff and was therefore privy to the changes that had to be made to Godfried prior to publication. Dr Scarsbrook explained in cross-examination as follows: ⁹¹

124 In re-examination Dr Scarsbrook explained further:

125 Further, even if etalons could be produced from WO 633/634, with birefringence within the SG 872 Range, it does not show that CVD diamonds suitable for use in etalons will be the inevitable result of following the directions in WO 633/634. The defendant could have conducted experiments on WO 633/634 to establish this, but did not do so. In the circumstances, Isberg is not evidence that a PSA, following the directions in WO 633/634 will inevitably produce a CVD diamond suitable for use in etalons.

126 Whitehead 2003 is an internal research report of the plaintiff dated 27 March 2003. ⁹² Whitehead 2003 discloses the properties of diamonds disclosed by the plaintiff to the RD42 Collaboration (“RD42”) before the priority date of SG 872, which were grown using the method in WO 633/634. According to the defendant, Whitehead 2003 discloses that these diamonds were suitable for use as etalons. Whitehead 2003 reproduced a cross-polarised image of the Type IIIa diamond and observed that “the only place where there is significant strain is at the boundary between the vertical and lateral growth”. Dr Nebel concluded from the cross-polarised image that the diamond in WO 633/634 would have been of low birefringence within the SG 872 Range.

127 I repeat my finding at [125] above. It is not sufficient for the defendant to show that selected CVD diamond material produced according to the directions WO 633/634 could be used as etalons. The test for anticipation requires a PSA, following the directions in WO 633/634, to inevitably produce a low birefringent diamond of requisite thickness within the SG 872 Range.

128 To conclude this section, the defendant has not proved the alleged correlations between on the one hand, breakdown electric field, Raman FWHM, charge collection efficiency and on the other, birefringence. Further, the defendant has also not proved that the CVD diamond in WO 633/634, while suitable to be used for detectors and anvils, necessarily had a birefringence value less than 10-4. In the circumstances, the defendant has not discharged its burden of showing that WO 633 and/or WO 634 anticipates Claim 1 of SG 872.

129 Given my finding that WO 633 and WO 634 do not anticipate Claim 1 of SG 872, it follows that various pieces of prior art with the same material would also not be anticipatory:

(a) Mara Bruzzi, “Status of the R&Ds on Diamond Particle Detectors”, presented at the 11th International Workshop on Vertex Detectors in November 2002.

(b) The disclosure of diamonds to the RD42 Collaboration, Bookham Technology and ABB Group Services Centre before 21 November 2002. These three disclosures were technical research collaborations in any event and obligations of confidentiality could be inferred from the circumstances and available documents: Strix Ltd v Otter Controls Ltd [1995] RPC 607.

130 SG 506 was filed on 19 September 2003 and claims a priority date of 20 September 2002 based on its priority document GB Patent Application No. 0221949.1 (“GB 949”). Although published on 1 April 2004, it is citable as prior art against SG 872 because of s 14(3) of the Patents Act, which is analysed in detail at [136]–[139] below. The plaintiff contends that the defendant has not proven that the SG 506 process would inevitably result in CVD diamonds with birefringence values in the SG 872 Range. ⁹³

131 The “Summary of the Invention” in SG 506 reads:

132 In essence, SG 506 relates to a method of improving the quality of substrates by growing a CVD diamond using the methods claimed in WO 633/634, and cutting a CVD plate from the grown diamond parallel to the growth direction. By repeating this process several times, it is claimed that the dislocation density of the resulting material will be greatly reduced: ⁹⁴

133 SG 506 discloses and enables the making of diamonds with dislocation densities of less than 50/mm2, 20/mm2, 10/mm2 and 5/mm2. According to Dr Nebel, diamonds with a dislocation density of less than 100/mm2 will have a birefringence of less than 10-4. Diamonds with a dislocation density of less than 10/mm2 will also have a birefringence of less than 5 x 10-5. These values fall within the SG 872 Range. I should also add that in its closing submissions, the defendant appears to also have conflated the SG 506 process with the WO 633/634 process, as it argues that “[SG 506] showed that the method claimed in [WO 633] and [WO 634] grew low birefringent diamonds”. ⁹⁵ It is evident, however, from the foregoing discussion that the general teaching in WO 633/634 and SG 506 are distinct, notwithstanding their areas of overlap.

134 According to the defendant, the diamond material produced from SG 506 is suitable for use as etalons. The defendant cites Example 1 of SG 506:

135 Although SG 506 was an unpublished patent application at the time of SG 872’s priority date, it is entitled to claim a priority date of 20 September 2002 from its priority document GB 949, and is therefore prior art.

136 As a preliminary objection, the plaintiff contends that Examples 1 and 2 of SG 506 are not citable for lack of novelty against SG 872, pursuant to s 14(3) of the Patents Act. ⁹⁶ Examples 1 and 2 of SG 506 are not relevant as they are not found in the priority document of SG 506 (ie, GB 949). Section 14(3) reads:

137 In order to determine the “priority date of that matter”, s 17(2)(b) is relevant:

138 Thus, an invention is entitled to claim priority from an earlier patent application if it is capable of being “supported by matter disclosed in the earlier relevant application”. However, a “matter” is only allowed to claim priority from an earlier application if it was “disclosed”.

139 In that regard, Examples 1 and 2 were not disclosed in the priority document of SG 506 (ie, GB 949). Accordingly, they are not relevant for the novelty inquiry.

140 I proceed to consider if Examples 1 and 2 of SG 506 anticipate Claim 1 of SG 872, on the assumption that they were disclosed in GB 949. In this connection, it should be noted that it is possible for specific examples in a prior patent to anticipate a later invention: see eg Jushi Group Co Ltd v OCV Intellectual Capital LLC [2019] RPC 1 (“Jushi”) at [44]; Liqwd Inc & Anor v L’Oreal (UK) Ltd & Anor [2018] EWHC 1394 at [193].

141 A PSA following the directions in Example 1 of SG 506 would produce diamond material “particularly suited to the application of etalons”. The question then is whether etalons must have a birefringence within the SG 872 Range. According to Dr Nebel, based on William S Gornall, “Interferometry Determines Wavelengths Precisely” (1997) Laser Focus World, etalons must have a birefringence of less than 7.7 x 10-5, and this falls within the SG 872 Range. ⁹⁷ In reply, Prof Newton merely stated that Dr Nebel’s calculation was “unsubstantiated”, but did not explain the basis for his view. In the circumstances, I prefer Dr Nebel’s evidence that etalons must have a birefringence within the SG 872 Range. I note that this is also consistent with Dr Scarsbrook’s evidence that the diamond material in WO 633/634 failed as etalons, whereas the SG 872 was suited for this purpose. ⁹⁸ In the circumstances, if Example 1 of SG 506 was relevant to the novelty inquiry, it would have, in my view, anticipated Claim 1 of SG 872.

142 In contrast, the general teaching in SG 506 does not anticipate Claim 1 of SG 872. Apart from the specific example taught in Example 1, there is nothing to suggest that a PSA following the broad teaching in SG 506 would invariably produce a diamond that is “suited to the application of etalons”, if the method used in Example 1 is not otherwise followed. In other words, Example 1 is a particular application of SG 506 with specific directions contained therein. The defendant could have conducted experiments to show that following the directions in SG 506, whether through the specific directions in Example 1 or otherwise, would inevitably result in a low birefringent CVD diamond within the SG 872 Range, but did not do so.

143 Example 2 of SG 506 reads:

144 Example 2 of SG 506 is not relevant to the novelty inquiry as it was also not disclosed in the priority document GB 949. In any event, while “the samples were used in an optical application which required very low scatter and birefringence”, there is no quantitative measurement of such birefringence (ie, it could be outside the SG 872 Range).

145 According to the defendant, Dr Bergonzo admitted that SG 506 would result in diamonds of lower birefringence than SG 872. The full extract reads: ⁹⁹

146 Read in its proper context, Dr Bergonzo’s evidence is that SG 506 relies on an extremely high quality substrate, which would not be used for SG 872. If the substrates were the same, the application of SG 872 would result in a diamond of lower birefringence than SG 506. This is evident from the chart drawn by the experts during a concurrent conference with the court and the court assessor, where Dr Bergonzo indicated using a black downwards arrow on the Y-axis for birefringence of the possible range of birefringence values for SG 506 (it is accepted by all parties that 806 refers to SG 506).

147 Therefore, Dr Bergonzo makes clear that a PSA, following the directions in SG 506, and using a superior substrate (“the birefringence might be lower if you take a substrate that will have less defects at the substrate”), would be able to produce a CVD diamond in the SG 872 Range, even without the controlled addition of low levels of nitrogen. That is entirely consistent with the express teaching in SG 506 itself, where Example 1 of SG 506 teaches the PSA to produce CVD diamond material suitable for use as etalons.

148 In the circumstances, SG 506 does not anticipate Claim 1 of SG 872 as following the general teaching in SG 506 will not inevitably result in a low birefringent diamond within the SG 872 Range. Much will depend on the quality of the starting substrate (for instance, the substrates produced according to Example 1 of SG 506).

149 Lastly I turn to the prior art which the defendant contends must result in the product of Claim 1, because of the identical methods asserted.

150 The defendant contends that SG 508, JP 890, Andrzej Badzian, “Synthesis of Diamond from the Gas Phase” in Electric Refractory Materials (Yukinobu Kumashiro, ed) (2000) ch 15 (“Badzian 2000”) and US 021 all constitute prior art that would anticipate Claim 1 of SG 872. This is as they “disclose methods that are identical to the method claimed in SG 872”. ¹⁰⁰ Thus, pursuant to the principle of inherent disclosure, following the directions in these prior art would lead to the growth of the same CVD diamond claimed in SG 872.

151 I reject the defendant’s contention that the methods in these prior art are identical to the one in SG 872. I will discuss the differences at [235]–[252] below. It suffices here to state that while SG 872 teaches the controlled addition of nitrogen within a specific range (300 ppb to 5ppm), none of the other prior art disclose this.

(a) SG 508 claims a priority date of 6 September 2002 from GB Patent Application No. 0220772.8 (“GB 772”). GB 772 discloses a broad range of nitrogen concentration between 0.5ppm to 500ppm, with the most preferred range being 2ppm to 30ppm. The examples in GB 772 use the same concentration of nitrogen in the synthesis process, 10ppm, which is twice the maximum amount of nitrogen allowed in SG 872 (5ppm). ¹⁰¹

(b) US 021 is a patent published in the United States on 12 December 1995. ¹⁰² The patent, however, teaches the PSA to remove impurities rather than to add nitrogen. In any event, the mere reference to “concentration of impurity components … is preferably not more than 500 ppm” would not inevitably lead a PSA following the directions in US 021 to use a nitrogen range of 300ppb to 5ppm (the SG 872 Range).

(c) JP 890 is a patent published in Japan on 24 October 1995. ¹⁰³ However, the nitrogen range disclosed in JP 890 is between 3ppm to 1000ppm. Again, there is nothing to suggest that a PSA will confine himself to a range of 300ppb to 5ppm such that a low birefringent diamond claimed by SG 872 will be produced.

(d) Badzian 2000 states that “CVD diamond growth with addition of gases like nitrogen influences step formation and eliminates twinning leading to smooth surfaces”. ¹⁰⁴ However, there is no indication of whether the influence of step formation and the elimination of twinning will lead to a reduction in birefringence. In so far as qualitative terms such as “near perfect” are used, these terms should be treated with caution, in the same way as the terms “low strain” or “low birefringence”.

152 I turn to the requirement of inventiveness, which is set out in s 15 of the Patents Act:

153 Therefore, unlike the novelty inquiry, the relevant state of the art for the inventiveness inquiry excludes unpublished patent applications which have a priority date earlier than the invention: s 15 read with s 14(3) of the Patents Act. For example, SG 506, which was only published on 1 April 2004, is not relevant for the inventiveness inquiry. In contrast, WO 633/634, which was published before the priority date of SG 872 (21 November 2002) are relevant pieces of prior art.

154 The rationale of the inventiveness requirement was stated by the Court of Appeal in First Currency Choice at [36]:

155 It should be stressed that when considering the question of inventiveness, it is assumed that the invention is novel and differs in some identifiable respect from the prior art: First Currency Choice at [19]. The burden is on the party resisting the patent claim to prove the absence of an inventive step: ASM Technology at [78]. Typically, the court engages in a four-step analysis also known as the Windsurfing approach, derived from the English decision of Windsurfing International Inc v Tabur Marine (Great Britain) Ltd [1985] RPC 59. This has been described as a “useful guide” for assessing inventiveness: First Currency Choice at [45]. In ASM Technology at [78], the Court of Appeal set out the Windsurfing approach as follows:

156 On the second step, the Court of Appeal noted in First Currency Choice at [38] that:

157 The observations of George Wei J in Rohm & Haas Electronic Materials CMP Holdings, Inc (formerly known as Rodel Holdings, Inc) v NexPlanar Corp and another [2018] 5 SLR 180 (“Rohm & Haas”) at [145] are also pertinent:

158 The Court of Appeal in Mühlbauer at [101] also considered the fourth step as being the “critical question”, with the first three steps “merely laying the ground work for this final question”. The assessment in the fourth step is to be made without the benefit of hindsight (ie, without the benefit of information available after the priority date), as an “ex post facto analysis … would be unfair to inventors”.

159 Unlike the novelty inquiry, it is permissible to “mosaic” the various pieces of prior art in the inquiry for inventiveness, unless the act of “mosaicing” itself is not obvious to the PSA. The mosaic “must be one which is put together by an unimaginative man with no inventive capacity”: Mühlbauer at [93]. The court can adopt a more “global approach”, rather than examine the various pieces of prior art individually vis-à-vis the patent: Mühlbauer at [96].

160 It should be noted that one way in which a patent may be inventive is if it overcomes existing prejudices held by the PSA: see Mühlbauer at [100]:

161 Further, the simplicity of the invention does not mean that the invention is obvious, or lacking in any inventive step: Mühlbauer at [102].

162 For present purposes, it is useful to refer to the Court of Appeal’s decision in Merck & Co Inc v Pharmaforte Singapore Pte Ltd [2000] 2 SLR(R) 708 (“Merck”). There, the product patent was for the compound Lovastatin with a dimeric impurity of less than 0.2%: Merck at [2]. The Court of Appeal found that the product patent was novel. The defendants failed to establish that following the teachings in the prior art would have inevitably led to the production of Lovastatin with less than 0.2% dimeric impurity: Merck at [42].

163 Notwithstanding, the product patent was held to lack an inventive step as it would have been obvious to a PSA working to purify Lovastatin that there were “standard” techniques which could be used to achieve that end (Merck at [64]–[65]):

164 Before turning to the inquiry proper, I should point out that the defendant has conflated its arguments between the novelty inquiry and the inventiveness inquiry, so far as Claim 1 of SG 872 is concerned. In asserting that Claim 1 of SG 872 is obvious, the defendant contends that “[i]t would have been obvious to a PSA looking at the state of the art before the priority date of [SG 872] that a low birefringent CVD diamond already existed”. ¹⁰⁵ An example of an argument made by the defendant in the inventiveness inquiry is as follows: ¹⁰⁶

165 However, as stated at [155] above, when considering inventiveness, it is assumed that the invention is novel and differs in some identifiable respect from the prior art: First Currency Choice at [19]. The defendant here, relying on Dr Nebel’s evidence, appears to have made the same error as the defendant in ASM Technology, by contending that the product claim does not involve an inventive step simply because it is anticipated by the prior art. That is the wrong approach: see ASM Technology at [80].

166 Dr Nebel’s evidence on the lack of inventiveness for Claim 1 of SG 872 was summarised by the defendant in its closing submissions. ¹⁰⁷ I reject the following arguments on the basis that they are premised on a finding that SG 872 is not novel:

(a) Claim 1 of SG 872 is obvious because:

(b) Claim 1 of SG 872 is obvious because:

(c) Claim 1 of SG 872 is obvious because:

I deal with the remaining arguments below.

167 In my view, the proper basis to determine if Claim 1 of SG 872 is inventive is to apply the Windsurfing approach, on the premise that the claim is novel.

168 Applying the four-step Windsurfing approach, the inventive step in Claim 1 of SG 872 is a CVD diamond of low optical birefringence within the SG 872 Range and of the requisite thickness (at least 0.5mm). The PSA seeking to reduce the optical birefringence of a CVD diamond would have regard to prior art such as WO 633/634. The difference between that prior art and Claim 1 of SG 872 is that the claimed CVD diamond is of a lower optical birefringence than the prior art.

169 The ultimate question, then, is whether the steps to be undertaken, in order to obtain a CVD diamond within the SG 872 Range, would have been obvious to a PSA. As with the PSA working on reducing impurities in Lovastatin in Merck, were there standard techniques available which could be used to reduce the optical birefringence of a CVD diamond to the SG 872 Range?

170 According to Dr Nebel, “[a] PSA would understand the need of using low defect density seeds and control of nitrogen in the growth atmosphere from Sumiya 1997”. In addition, JP 890 “teaches a PSA that growing a diamond with [a] ‘controlled low level of nitrogen’ will reduce the defects” [original emphasis omitted]. ¹⁰⁸ In other words, Sumiya 1997 would teach the need to select a substrate with low defect density, and JP 890 would teach the addition of trace amounts of nitrogen.

171 Therefore, according to Dr Nebel, “a PSA will know from reading Sumiya 1997 and JP 890 that a diamond grown with a good quality seed and low nitrogen will have very low strain and therefore very low birefringence”. ¹⁰⁹

172 I reject Dr Nebel’s assessment, as it is not clear how a PSA would be able to obtain the nitrogen range of 300ppb to 5ppm from Sumiya 1997 and/or JP 890. In fact, as the plaintiff rightly points out, a PSA reading JP 890 would add nitrogen concentration above 30ppm and not between 300ppb and 5ppm. ¹¹⁰ JP 890 is primarily concerned with growth rate; it teaches the PSA how “[t]o synthesize high quality diamond in a vapour phase at a high rate of synthesis”. The growth rate discussed in JP 890 only substantially increases when the nitrogen concentration is above 30ppm. Further, JP 890 also does not disclose that the addition of low levels of nitrogen would result in a reduction in birefringence. It would thus not have been obvious to a PSA to add nitrogen in the range of 300ppb to 5ppm to obtain a low birefringent CVD diamond in the SG 872 Range.

173 Next, Dr Nebel relies on both Sumiya 1997 and US 412 (published on 19 December 2000) ¹¹¹ to contend that Claim 1 of SG 872 is obvious. Dr Nebel’s argument is that Sumiya 1997 “discloses that a diamond with less than 0.1 ppm nitrogen content will have very low strain due to the absence of defects introduced by nitrogen”. ¹¹² As for US 412, it “teaches a PSA that to achieve a diamond with nitrogen content of less than 0.2 ppm, the nitrogen in the synthesis gas phase should not exceed 1ppm”. ¹¹³

174 Therefore, according to Dr Nebel, a PSA reading Sumiya 1997 and US 412 together, would “understand that to achieve a low birefringent CVD diamond, one should use a low defect density seed and limit the nitrogen in the synthesis gas phase to below 1 ppm to achieve a low strain and low birefringent diamond”. ¹¹⁴

175 I reject Dr Nebel’s contention. It is hard to see how Sumiya 1997 read with US 412 would teach the PSA that adding low levels of nitrogen between 300ppb and 5ppm would result in a reduction of birefringence. As Dr Bergonzo noted, US 412 states: ¹¹⁵

176 Far from teaching the PSA that the deliberate addition of nitrogen will reduce birefringence, US 412 would have, consonant with the common general knowledge, taught the PSA that the addition of nitrogen would result in a “deterioration of the diamond quality”. In my view, it would not have been obvious to a PSA reading Sumiya 1997 and US 412 that the deliberate addition of nitrogen would result in a reduction of birefringence. A PSA reading US 412 would instead do the converse (ie, remove instead of add nitrogen).

177 According to the defendant, US 430 “teaches a PSA that annealing a diamond will reduce its optical birefringence”. ¹¹⁶ A PSA reading US 430 with WO 633, WO 634, Isberg, Bruzzi, US 021, Badzian 2000, JP 890 and US 932 “will know that annealing the diamonds disclosed in these prior art will further reduce the optical birefringence of these diamonds”. ¹¹⁷

178  It is not necessary for me to deal with this contention at length, as Dr Nebel’s evidence in cross-examination was that a PSA would not anneal a diamond to reduce its birefringence. Instead, the PSA would look to the quality of the substrate instead: ¹¹⁸

179 Next, I consider the argument that Claim 1 of SG 872 lacks inventiveness because a PSA would improve the quality of substrates to grow low birefringent CVD diamonds in the SG 872 Range. To be clear, the defendant did not raise this argument in its closing submissions. However, as Dr Nebel alluded to this possibility in cross-examination (see [178] above), I deal with this for completeness.

180 In my view, a PSA might have known that improving the quality of substrates would lead to a low birefringent CVD diamond in the SG 872 Range. However, the obtaining of that high quality substrate would in and of itself have involved an inventive step. This is because no substrate of the requisite quality was available at that date. The PSA, being an “unimaginative” technician, would not be expected to make that inventive step.

181 Prof Newton accepted that a PSA using a high quality substrate could obtain a low birefringent CVD diamond in the SG 872 Range. But such a substrate was not available as of the priority date of SG 872, and it would not have been obvious how such a substrate could be obtained. ¹¹⁹ This was not refuted by the defendant, save that it asserts that such a substrate preparation is found in in SG 506, which teaches a two-stage growth process, and specifically Example 1 of SG 506. To recapitulate, SG 506 is a method of improving the quality of substrates by growing a CVD diamond using the method claimed in WO 633/634 and cutting a CVD plate from the grown diamond parallel to the growth direction. By repeating this method of growing and cutting the substrate, the dislocation density of the resulting substrate will be reduced. Thereafter, a low birefringent CVD diamond can be grown on top of this high quality substrate using WO 633/634.

182 A PSA who has read SG 506, and specifically Example 1 of SG 506, would have known how to obtain low birefringent CVD diamonds within the SG 872 Range. This is because Example 1 teaches that the diamond material produced from that method are suitable for use as etalons, and I have accepted that etalons must have a birefringence within the SG 872 Range. Nevertheless, and importantly, SG 506 was only published on 1 April 2004. It would thus not have been obvious to a PSA as of the priority date of SG 872 (21 November 2002) how to obtain this high quality substrate through the technique taught in Example 1 of SG 506. SG 506 is itself a valid patent and there is no contention by the defendant that it lacks novelty or an inventive step.

183 In this context, I deal with two articles cited also for novelty, despite their being made after the priority date.

184 To prove that WO 633 anticipated SG 872, Dr Nebel cites Friel et al, “Control of surface and bulk crystalline quality in single crystal diamond grown by chemical vapour deposition” (2009) 18 Diamond & Related Materials 808 (“Friel 2009”) where the samples fell within the SG 872 Range. ¹²⁰ Dr Nebel relies on a reference to endnote 16 to WO 633 and WO 427 (on which SG 872 is based). Dr Nebel points out that this means that either the method claim in WO 633 or SG 872 would result in low birefringent diamonds within the SG 872 Range. However, Prof Newton points out that Friel 2009 discloses a two-stage process of growing diamonds. While both WO 633 and WO 427 were cited, it is unclear that either would have resulted in a low birefringent diamond within the SG 872 Range. Another way of reading endnote 16 is that one or both of the two stages in Friel 2009 involved WO 427, which would explain the low birefringent diamonds in the SG 872 Range. In any event, even if the defendant’s interpretation of the reference to endnote 16 is right, Prof Newton also highlighted that the substrate used in Friel 2009 would not have been available as of the priority date of SG 872. This meant that a PSA, following the directions in WO 633/634 would not have been able to produce a low birefringent diamond in the SG 872 Range. Dr Nebel agreed that the substrate in Friel 2009 would not have been available as of the priority date of SG 872: ¹²¹

185 Dr Nebel relied on Tallaire et al, “Thick CVD diamond films grown on high-quality type IIa HPHT diamond substrates from New Diamond Technology” (2017) 77 Diamond & Related Materials 146 (“Tallaire 2017”) to prove that WO 633/634 would result in a low birefringent diamond in the SG 872 Range. However, as with the substrate used in Friel 2009, the New Diamond Technology (“NDT”) substrate is new and was not available as of the priority date of SG 872, such that a PSA following the directions in WO 633/634 would not inevitably produce a low birefringent diamond in the SG 872 Range. Dr Nebel accepted that the NDT substrate was new in cross-examination: ¹²²

186 Commercial success may be used as a relevant factor in determining inventiveness: see Mühlbauer at [107]. It is clear from the prior art discussion that the product fulfilled a need in the optical applications market. As I have held that the product in SG 872 is inventive on other grounds, I do not deal with this issue.

187 The “enabling disclosure” or “sufficiency” requirement is found in s 25(4) of the Patents Act:

188 Section 80(1)(c) of the Patents Act provides that the patent may be revoked if s 25(4) is not satisfied.

189 In First Currency Choice, the Court of Appeal adopted the two-stage test set out by Lord Hoffmann in Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2005] RPC 9 at [103]: First Currency Choice at [61]–[62]:

190 In addition, the following principles are also relevant:

(a) Whether the specification of a patent discloses the invention clearly enough and completely enough for it to be performed by a PSA is a question of degree. The question of the sufficiency of the disclosure is a matter of fact, depending on the nature of the invention and the other circumstances of the case: First Currency Choice at [60].

(b) It is insufficient for the party seeking to invalidate the patent to merely highlight ambiguities in the claims. Instead, the burden of proof is on that party “to show that those ambiguities would render the invention unworkable from the point of view of a person skilled in the art who is trying to give practical meaning to the patent specification”: Rohm & Haas at [158], citing Susanna H Leong, Intellectual Property Law of Singapore (Academy Publishing, 2013) at para 16.271). The PSA possesses common general knowledge and common sense as befits the area of technology in question: Rohm & Haas at [159].

(c) The breadth of the claims is relevant to an assessment of the sufficiency requirement. If the invention discloses a principle capable of general application, the claims may be in correspondingly general terms: First Currency Choice at [60].

191 The defendant relies on s 25(5) of the Patents Act, which states as follows:

192 This “clarity” requirement is not, however, a ground for revocation under the Patents Act (see First Currency Choice where the Court of Appeal made clear at [72] that, “where the specification of a patent is sufficient, any potential ambiguity or undue breadth of a claim is not in itself a ground of revocation”). What is important is whether the claim discloses the invention sufficiently for a PSA to perform it.

193 I now turn to the defendant’s contentions on why Claim 1 of SG 872 is insufficient.

194 The diamond material claimed in Claim 1(ii) of SG 872 requires the mod sine delta “for at least 98% of the analysed area of the sample” to remain in first order (where delta does not exceed π/2) and for the mod sine delta not to exceed 0.9.

195 However, according to the defendant, a PSA using the Metripol will not be able to identify whether the optical birefringence of the diamond is in first order (defined as delta not exceeding π/2). ¹²³ This is because the Metripol only measures mod sine delta as an absolute value, and it is “impossible” to determine from the value of mod sine delta whether delta does not exceed π/2 because the value of mod sine delta repeats itself at every interval of π and each range of π has two possible values of delta. ¹²⁴

196 This alleged problem can be illustrated through the following diagram produced by Dr Kaminsky:

197 The defendant notes that this was an issue that was already foreseen by Dr Glazer and Dr Kaminsky when they co-wrote the first publication for the Metripol (then known as Deltascan) in 1996, “An Automatic Optical Imaging System for Birefringent Media” (2996) 452(1955) Proc R Soc Lond A 2751(“Glazer 1996): ¹²⁵

198 Notwithstanding the solution identified in Glazer 1996, Dr Kaminsky’s evidence was that this would not be “sufficient advice” to determine the order as the “[m]ethods applied in polarized light microscopy referred to in [Glazer 1996] are insufficient to identify δ < π/2 in highly heterogeneous samples”.

199 The plaintiff advances several responses to Dr Kaminsky’s criticism. First, it contends that since first order is expressly defined in SG 872 as delta not exceeding π/2, the PSA would only need to look at the value indicated in the first quadrant. But, in my view, this somewhat circular response does not directly address Dr Kaminsky’s point; it does not provide an explanation as to how the PSA can determine that the optical birefringence of the diamond is in first order.

200 Second, Dr Glazer provided the following solution, which he claimed the PSA would have known:

201 The defendant, however, submits that this solution is unworkable, relying on the following image:

202 According to the defendant, each of the five yellow boxes would satisfy Dr Glazer’s requirement where the values for mod sine delta range from 0 upwards to 1 but does not extend close to 1. However, only “Box 1” will satisfy the requirement where delta does not exceed π/2. ¹²⁶ Dr Glazer’s explanation was as follows: ¹²⁷

203 Dr Glazer further explained: ¹²⁸

204 I accept the logic of Dr Glazer’s explanation. In essence, Dr Glazer’s explanation is that birefringence is a “continuous function”. Once presented with a gap between the mod sine delta value nearest 1 and 1, the PSA would understand that this “corresponds to one continuous range of [delta] values extending from close to 0 to a value that is less than π/2” [emphasis added]. The patent makes this expectation clearer by specifying that the mod sine delta is to remain in the first order where delta does not exceed π/2. Conversely, if delta extended to the second order and beyond, the PSA would expect there to be values in those gaps. The presence of the gaps would thus “not make scientific sense” if delta exceeded π/2.

205 Relatedly, the defendant contends that there is an “inherent flaw” in the Metripol as it is incapable of displaying mod sine delta values close to one. ¹²⁹ The gap in mod sine delta values, which Dr Glazer refers to, is not because delta is limited to less than π/2, but because the Metripol has an “incurable fault”. For this contention, the defendant relies on Dr Kaminsky’s evidence. But it is clear that Dr Kaminsky made no such argument. I accept the plaintiff’s reply that Dr Kaminsky’s evidence was referring to the mod sine delta values of Sample 2, which he alleged was a multi-layer sample causing depolarisation, rather than to the Metripol generally. ¹³⁰ Dr Kaminsky stated as follows: ¹³¹

206 Finally, the defendant also relies on the Metripol results for Samples 2, 3 and 4 to prove that Dr Glazer’s solution is unworkable. ¹³² In the Metripol measurements of Samples 2, 3 and 4, the values of mod sine delta range from 0 upwards to 1 but do not extend close to 1. According to the defendant, this means that the whole of Samples 2, 3 and 4 would have birefringence in the first order where delta is less than π/2. In fact, this is an inaccurate characterisation of the Metripol tests, which were completed within the analysed area of Claim 1(ii) of SG 972.

207 I turn to Dr Kaminsky’s argument that the Metripol is unable to measure birefringence for samples thicker than 0.25mm, as the objective of the microscope used for the Metripol has a depth of field of only 0.25mm. ¹³³ Given that Claims 1(ii) and 1(iii) of SG 872 require the diamond material to have a minimum thickness of 0.5mm, it is alleged that the Metripol would not be able to measure the birefringence accurately across the thickness of the diamond material. ¹³⁴ According to Dr Kaminsky: ¹³⁵

208 In response to Dr Kaminsky’s evidence, the plaintiff points out that single crystal CVD diamond is homogeneous along the light path so that any birefringence along that light path remains approximately constant. In Dr Glazer’s words: ¹³⁶

209 Consequently, the entire depth of the sample being analysed does not have to be in focus.

210 Dr Kaminsky’s evidence on the lack of homogeneity in CVD single crystal diamonds ought to be seen in the light of his candid acceptance in cross-examination that he had not “touched a diamond” for 30 years, ¹³⁷ and that he could not comment on dislocations in diamonds. ¹³⁸ I accept Dr Glazer’s evidence, which is further confirmed by the following points.

211 The defendant points out that Dr Glazer did not account for the fact that while dislocations propagate generally in parallel to the growth direction, they spread outwards as the diamond grows thicker. ¹³⁹ This, according to the defendant, is evidenced by Claim 46 of SG 872, which Dr Nebel had referred to in his presentation to the court for the proposition that “dislocations do not grow straight”:

212 In my view, Dr Nebel and Dr Glazer are in fact in agreement that dislocations run close to parallel to the growth direction in CVD diamond: see also Prof Newton at [51]. Notwithstanding that Dr Nebel had referred to Claim 46 of SG 872, this was not meant to qualify the general proposition that dislocations run through the diamond “nearly perpendicular” to the growth direction. In fact, Dr Nebel doubted whether CVD single crystal diamond material could have an “average dislocation direction in the plate more than 30° from normal to the major faces”, as stated in Claim 46. Dr Nebel’s evidence that “dislocations do not grow straight” ought to be seen in the context of the following passage from cross-examination: ¹⁴⁰

213 That the experts are in agreement on this point is also evidenced by the following:

(a) In C Holly et al, “Monocrystalline CVD-diamond optics for high-power laser application” (2016) , a paper co-authored by Dr Nebel, it is stated that:

(b) Dr Nebel also confirmed in cross-examination that “dislocations grow in the direction of growth”, which could be checked by x-ray topography. ¹⁴¹

(c) Dr Kaminsky accepted in cross-examination that “for single crystal CVD diamonds, the growth is basically in one direction, the vertical direction, from seeds or substrates which are placed in the CVD reactor”. ¹⁴² Further, the direction of growth could be confirmed with x-ray topography. ¹⁴³

214 The defendant also raises several other points relating to the depth of field, which I reject and deal with briefly.

215 First, the defendant claims that Dr Newton contradicted Dr Glazer’s evidence by stating “dislocations can multiply during growth. As growth means increasing thickness, it is apparent that dislocations multiply with increasing thickness”. ¹⁴⁴ In my view, there is no contradiction between Dr Newton and Dr Glazer’s evidence. It is one thing to say that dislocations multiply during growth, and therefore the dislocations between a sample of, for example, 0.25mm, might vary from one that is 0.5mm. But that does not detract from the point that in a given CVD diamond, in Prof Newton’s own words, “the dislocations typically run approximately paralleled and in the growth direction”: see [51] above. Consequently, the strain fields tend to show little variation through the depth of a sample.

216 The defendant also claims that taking Dr Glazer’s points at their highest, the PSA is required to know in which direction the sample has been cut with respect to the growth direction. According to the defendant, a diamond plate that is cut 90° to the growth direction of the diamond will have dislocations that are different from a diamond that is cut at any angle to the growth direction of the diamond. ¹⁴⁵ In my judgment, this point is neither here nor there. Even if one assumes that the defendant is right, it simply means that the resulting diamond material may not satisfy the requirements of Claim 1(ii) or 1(iii) of SG 872, and therefore not be infringing. This argument has no relevance to the depth of field, and whether Claim 1 satisfies the enabling disclosure or sufficiency requirement.

217 Finally, I turn to the experiments conducted by Dr Glazer and Dr Kaminsky to prove their respective hypothesis. On Dr Glazer’s part, he conducted an experiment on sample NL 719-05 (single crystal CVD diamond), with a thickness of 0.52mm. By measuring the top, middle and bottom of this sample, Dr Glazer concluded that “the fact that the sample thickness is significantly greater than the depth of field of the microscope objective has no significant effect on the [mod sine delta] maps for such samples”. ¹⁴⁶ As for Dr Kaminsky, he conducted a similar experiment on a 1.9mm thick salt crystal. Dr Kaminsky measured the top, middle and bottom of the salt crystal by changing the focal height of the microscope, and found that there was a “marked difference” in the details of the salt crystal at each focal height. ¹⁴⁷

218 It is telling that Dr Kaminsky decided to do his experiment on table salt rather than diamonds. Given that the subject matter at hand was CVD diamonds, and Dr Kaminsky could have obtained CVD diamonds from the defendant, one would have thought that it would have behoved Dr Kaminsky to conduct his experiment on CVD diamonds instead. On this point alone, one is able to place more weight on the results of Dr Glazer’s evidence.

219 Further, as would have been plain to Dr Kaminsky, the atomic structure between diamond and table salt (ie, sodium chloride) is different. The refractive index of salt is also lower such that there is no optical equivalence, resulting in more defocussing in salt. The sample used by Dr Kaminsky was also several times thicker than the CVD diamond material disclosed in the specifications of SG 872 (1.99mm vs 0.5–0.8mm). ¹⁴⁸ It is therefore unsurprising that Dr Kaminsky had referred to this experiment as “a very extreme case”. ¹⁴⁹

220 I have decided Claim 1 is valid. It will also be clear from the infringement analysis, at [456], that the Claim 62 process with a higher level of nitrogen incorporation leaves a marker within the product. For example, WO 633 and WO 634 state that the concentration of single substitutional nitrogen in the diamond is in a range below 7.04 x 1015 atoms/cm3 (ie, below 40ppb) and below 1.76 x 1016 atoms/cm3 (ie, below 100ppb). ¹⁵⁰ However, the nitrogen concentration in a SG 872 diamond is higher given that there is more nitrogen incorporation. This is reflected in Claims 57 and 58 of SG 872 which claim for a range of below 5 x 1017 atoms/cm3 (ie, below 2.84 ppm) and below 2 x 1017 atoms/cm3 (ie, below 1.136ppm) respectively. Therefore, Claims 57 and 58, which make clear the difference in nitrogen structure between WO 633/634 diamonds and SG 872 diamonds, are also valid product claims read with Claim 1.

221 I do not deal with any other claims save for Claim 62, which was fully canvassed at trial.

222 I turn to Claim 62, which states as follows:

223 The plaintiff frames the inventive concept of the process claim in SG 872 as follows: ¹⁵¹

224 There is no dispute that the priority date of Claim 62 is 21 November 2002. ¹⁵²

225 It is common ground between the parties that Claim 62 has three essential integers (with non-essential integers being irrelevant in deciding whether there is infringement, see First Currency Choice at [77]): ¹⁵³

(a) A substrate substantially free of crystal defects, whereby the density of defects at the surface of the substrate is below 5 x 103/mm2;

(b) The substrate undergoes a plasma etch on the surface on which homoepitaxial diamond growth is to occur; and

(c) A provision of a source gas and dissociating the source gas to produce a synthesis atmosphere which contains 300ppb to 5ppm nitrogen, calculated as molecular nitrogen.

226 I deal preliminarily with the treatment of anticipation of ranges as it is relevant to the approach to be taken to the prior art alleged. Claim 62 of SG 872 teaches the deliberate and controlled addition of nitrogen in the range of 300ppb to 5ppm. The defendant, in approaching the prior art, asserts that it is sufficient if a prior art discloses a single value that falls within the Claim 62 range. Where there is an overlap in ranges but no specific example in the range of overlap, on the basis of the IPOS Examination Guidelines paragraphs 3.50-2, it asserts there is anticipation if a PSA would have seriously contemplated applying the prior art in the region of overlap.

227 This issue of anticipation of ranges was dealt with the English Court of Appeal in Jushi, where the invention claimed was a glass fibre or “strand” for inclusion as reinforcement in other materials such as glass-reinforced plastic. The relevant claim, Claim 1, read as follows (Jushi at [6]):

228 The prior art that was considered by the English Court of Appeal, and referred to in the patent itself, was US Patent 4 199 364 (“Neely”). Neely disclosed boron and fluorine-free glass compositions for producing glass fibres. The relevant table was as follows (Jushi at [17]–[18]):

229 It was common ground in Jushi that the range of each of the constituents in Table IV either fell within or overlapped with the corresponding ranges in Claim 1 of the patent: Jushi at [19]. The question was whether Table IV deprived Claim 1 of novelty.

230 The English Court of Appeal noted the following principles as being pertinent:

(a) In general, a broad generic disclosure in the prior art does not take away the novelty of a claimed more specific one, citing Dr Reddy’s Laboratories (UK) Ltd v Eli Lilly and Co Ltd [2010] RPC 9 (“Dr Reddy”) at [28]–[29]. In Dr Reddy, a broad disclosure of tens of thousands of chemical compounds did not take away the novelty of a claim to a single compound. This was because when one had “a patent for a particular chemical compound and a prior art general disclosure, performance of the general disclosure (which means no more than using anything within it) does not necessarily result in infringement of the patent” [emphasis added]: Dr Reddy at [30]–[32].

(b) The issue of whether the prior art contains a disclosure of the invention will often depend on how the prior art would be understood by the PSA, taking account of the common general knowledge: Jushi at [47].

231 In Jushi, Floyd LJ expressed reservations about the serious contemplation test which I have referred to at [226]. Referring to his previous decision in H Lundbeck A/S v Norpharma SpA [2011] RPC 23, he explained at [49] that there is no disclosure of the narrower range. If no specific individual value is disclosed, there would be no clear directions to use a value within the narrower range. A person carrying out the disclosure of the prior range will not inevitably fall within the claim of the later patent.

232 Ultimately, the English Court of Appeal held that the serious contemplation test does not materially differ from the conventional approach to novelty expounded in Synthon BV v Smithkline Beecham plc [2006] RPC 10 and Dr Reddy. However, it was preferable to treat the latter cases as the relevant yardstick: Jushi at [51]. That being the case, the court noted that the plaintiff did not point to anything in the prior art which taught the PSA that they should operate in the area of combined overlap of those ranges: Jushi at [52].

233 The English Court of Appeal then dealt with the question of whether it could be said that each and every combination of values had been disclosed in Neely, and at least of fraction of those combinations would fall within Claim 1 of the patent. As a matter of law, however, this submission was inconsistent with the principle in Dr Reddy – that a broad disclosure does not take away the novelty of a claim to a specific example or recipe: Jushi at [53]. Further, on the facts, the PSA would not have understood Neely to be telling them that one could indiscriminately choose any combination of values in Table IV: Jushi at [54]. Accordingly, the invention in Claim 1 of the patent remained concealed or hidden in the disclosure of Neely: Jushi at [56].

234 I adopt the same approach as Jushi in the present case. When dealing with overlapping ranges, the question to be asked is whether the prior art taught the PSA that they should operate in the area of the combined overlap of the ranges. Turning to the present case, the question to be answered for the novelty inquiry is thus whether carrying out the directions in the prior art will inevitably result in an infringement of Claim 62.

235 I turn to the prior art cited by the defendant in its closing submissions. First, the defendant claims that SG 508 anticipated Claim 62 of SG 872. While SG 508 relates to a method of changing the colour of CVD by annealing (which I discuss in detail below), the specifications of SG 508 teach the growth of a CVD diamond “using the same process” as claimed in SG 872. ¹⁵⁴

236 Although SG 508 was published after the priority date of SG 872, it is citable as prior art as it claims priority from GB 772, which has a priority date of 6 September 2002: see s 14(3) Patents Act.

237 According to the defendant, a PSA who uses the process described in GB 772 and SG 508 would have infringed Claim 62 of SG 872. The dispute here centres on the range of nitrogen disclosed in SG 508 which states as follows:

238 I also note that the defendant has cited two examples in SG 508, where the gas mixture is said to include 2.5ppm (Example 4) and 3.8ppm (Example 6) respectively. ¹⁵⁵ However, these two examples are not disclosed in the priority document GB 772. ¹⁵⁶ They are therefore not relevant to the novelty inquiry: see the analysis at [136]–[139].

239 SG 508 in fact only contains three examples which were disclosed in GB 772 (Examples 1 to 3). In these examples, nitrogen was introduced into the growth process at a concentration of 10ppm. ¹⁵⁷ The relevant question then is whether a PSA reading SG 508/GB 772 would be taught to add a nitrogen concentration in the combined region of overlap (ie, 0.5ppm to 5ppm). In my view, given that that most preferred range of nitrogen was stated to be between 2ppm and 30ppm, and that the examples expressly stated that nitrogen was introduced at 10ppm, this would have pointed the PSA away from operating at the combined region of overlap (ie, 0.5ppm to 5ppm). There is nothing in SG 508 which teaches the PSA not to use nitrogen above 5ppm. To the contrary, the PSA would be taught by Examples 1 to 3 of SG 508 to use nitrogen at 10ppm.

240 SG 508 therefore does not anticipate Claim 62 of SG 872.

241 Badzian 2000 was concerned with the growth of “nearly perfect crystals”. So far as the addition of nitrogen is concerned, it is stated as follows: ¹⁵⁸

242 According to Dr Nebel, the “addition of small amounts of nitrogen” described in Badzian 2000 is the equivalent of the addition of 300ppb to 5ppm in SG 872. ¹⁵⁹ I reject this contention. There is no nitrogen range set out in Badzian 2000, let alone one that overlaps with Claim 62 (as in SG 508). Following Dr Reddy, the generic disclosure of the addition of nitrogen does not take away the novelty of the specific range claimed in SG 872. There is nothing in Badzian 2000 which teaches the PSA to confine the use of nitrogen to the range of 300ppb to 5ppm.

243 Accordingly, Badzian 2000 does not anticipate Claim 62 of SG 872.

244 US 021 relates to a technique for producing CVD diamonds which can be used for semiconductor material, electronic and optical components. ¹⁶⁰

245 There was some debate between the experts, Dr Bergonzo and Dr Nebel, over whether the teaching in US 021 was to remove nitrogen altogether, or to add nitrogen as a source gas. In any event, the nitrogen range which is referred to in US 021, found in Example 1, teaches the PSA to add nitrogen between 5 and 20ppm. However, the range in Claim 62 is 300ppb to 5ppm. There is nothing in US 021 which would confine the PSA to only use nitrogen at 5ppm and not a higher concentration.

246 Thus, US 021 does not anticipate Claim 62 of SG 872.

247 I have dealt with JP 890 at [172] above in the context of the inventiveness of Claim 1 in SG 872. JP 890 is a patent which teaches the PSA how to grow high quality diamonds “at a higher rate of synthesis”. The references to the addition of nitrogen ought to be seen in that context. For present purposes, the defendant highlights the following quotations from JP 890: ¹⁶¹

248 Table 1 of JP 890 states as follows:

249 According to the defendant: ¹⁶²

250 JP 890 merely teaches the PSA to add a “trace amount of nitrogen” to “provide a higher quality diamond at a higher rate of synthesis”. The nitrogen concentration is quantified in the “first invention of the present application” as being 1.5ppm to 500ppm. The question then is whether the PSA would confine themselves to the combined range of overlap with Claim 62 of SG 872 (ie, 1.5ppm to 5ppm).

251 In my judgment, there is nothing in JP 890 which teaches the PSA not to add nitrogen above 5ppm. In fact, from Table 1 of JP 890, it shows clearly that the growth rate of the CVD diamond only increases when 30ppm of nitrogen is added. This was the teaching of JP 890.

252 Accordingly, JP 890, as with SG 508, Badzian 2000 and US 021, does not anticipate Claim 62 of SG 872.

253 I turn to the inventiveness inquiry for Claim 62 of SG 872. Applying the Windsurfing approach:

(a) Step 1: The inventive concept in Claim 62 of SG 872 is the deliberate and controlled addition of nitrogen between 300ppb and 5ppm in the synthesis atmosphere, to reduce dislocations in the resulting material which will be of lower optical birefringence.

(b) Step 2: The common general knowledge as of the priority date of SG 872 was the addition of nitrogen would speed up the growth rate of CVD diamonds. However, the common general knowledge at the material time was that the addition of nitrogen would increase birefringence. Indeed, this is still the view held by Dr Nebel, as illustrated in the chart drawn by Dr Nebel and Dr Bergonzo.

(c)  Step 3: The difference between the prior art and the claimed invention relates to the addition of nitrogen in the synthesis atmosphere within the controlled range of 300ppb to 5ppm, in order to obtain CVD diamond material of low birefringence in the SG 872 Range.

(d) Step 4: The question, therefore, is whether it would have been obvious to the PSA seeking to obtain a low birefringent diamond in the SG 872 Range that they should add nitrogen within the controlled range of 300ppb to 5ppm in the synthesis atmosphere.

254 The inventive concept of Claim 62 was contrary to the common general knowledge as of 21 November 2002. As Prof Newton explained: ¹⁶³

255 Dr Nebel confirmed that for CVD diamonds, “the thinking was [that] nitrogen causes a variety of defects to be formed or present”. ¹⁶⁴ Further, it was understood as at November 2002 that “[a]dding more nitrogen would … increase strain”. ¹⁶⁵

256 Consequently, nitrogen was seen as an impurity or contaminant which ought to be reduced to the lowest practical levels possible. ¹⁶⁶ What SG 872 taught was that contrary to this common general knowledge, the deliberate and controlled addition of nitrogen between a specified window of 300ppb to 5mm would reduce strain resulting from dislocations in the CVD material, therefore improving the optical properties in the CVD diamond material. In this regard, it is useful to refer to Dr Bergonzo’s evidence: ¹⁶⁷

257 The defendant disputes inventiveness not by contending that the concept was obvious, but rather, that the concept did not result in the practical effect claimed. Its assertion was that the addition of nitrogen is only to increase the growth rate (ie, to allow for the growth of low birefringent diamonds at a commercially viable rate). ¹⁶⁸ Its position is that “the addition of nitrogen will increase the optical birefringence in the grown diamond because nitrogen will introduce defects into the diamond”. ¹⁶⁹

258 I had referred earlier to Example 9 of SG 872 which supports the inventive concept of Claim 62: see [97]. That the focus of Claim 62 was to obtain a CVD diamond of lower optical birefringence, as opposed to improving the growth rate, is also supported by JP 890, which shows that the growth rate only increases significantly when nitrogen of 30ppm is added. Dr Nebel had also referred to the relevant table in JP 890 in his 2nd AEIC, discussed in detail at [248] above. ¹⁷⁰

259 The defendant does not attempt to disprove positively the plaintiff’s contention on the effect of the addition of the small amount of nitrogen. Instead it contends that the plaintiff has made admissions to the contrary. The defendant refers to the plaintiff’s own patent WO 2015/071484 (“WO 484”) filed on 18 November 2014, which purportedly contains an admission from the plaintiff that nitrogen was introduced to “increase growth rates while not being so high as to unduly affect optical properties”: ¹⁷¹

260 The plaintiff however points out that in another section of WO 484, it is stated as follows: ¹⁷²

261 WO 484 therefore does not assist the defendant’s case. It is not disputed that the addition of large amounts of nitrogen would speed up the growth of CVD diamonds. At the same time, the plaintiff’s contention in Claim 62 is that the addition of a specific amount of nitrogen would lower the birefringence. The plaintiff highlights that in the defendant’s own patent, WO 2016/144256, the dual effects of nitrogen are also stated: ¹⁷³

262 The defendant also relies on purported admissions by Dr Scarsbrook, Dr Newton and Dr Bergonzo made during trial. However, read in context, it is clear that none of them had admitted that the addition of nitrogen was only to increase the growth rate of CVD diamonds.

263 First, Dr Scarsbrook’s purported admission is said to be found in the following extract: ¹⁷⁴

264 It is clear, therefore, that Dr Scarsbrook did not admit that the addition of nitrogen was only to increase the growth rate CVD diamond. In fact, he had expressly stated that the addition of nitrogen would result in a reduction in strain, stress and hence birefringence. On that note, I should also highlight that Dr Scarsbrook explained that there was a distinction to be drawn between a pure and perfect diamond: ¹⁷⁵

265 Next, the defendant also contends that Prof Newton made a similar “admission”, relying on the following passage: ¹⁷⁶

266 Thus, Prof Newton’s opinion was that the prior art, being WO 633 and WO 634 could produce low birefringent CVD diamonds within the SG 872 Range but only because of the improvement in substrates post-dating the priority date of SG 872.

267 Dr Bergonzo’s “admission” is said to be contained in the following extract: ¹⁷⁷

268 Nowhere in this passage does Dr Bergonzo say that the only effect of the adding nitrogen is to increase the growth rate of CVD diamonds. Further, Dr Bergonzo had expressly qualified his answer and did not agree that SG 506 would result in the “very same low birefringent diamonds” as in SG 872. I should also note that there is no inconsistency in stating that the controlled addition of low levels of nitrogen reduces birefringence in the CVD diamond and therefore allows the production of diamond material suitable for optical applications in a manner that is commercially viable.

269 For completeness, I close this section with the observation that the experts’ inability to explain why nitrogen would have the desired effect is irrelevant. In Merrell Dow, the plaintiff was able to patent terfanadine, an anti-histamine drug which did not have the side effect of making one drowsy, notwithstanding the fact that it was not understood precisely at the time of its first patent why there was no side effect: see Merrell Dow at [5]. The defendants’ submission criticising the plaintiff’s inability to explain the “strange effect” of nitrogen, in Prof Newton’s words, is therefore wholly unmeritorious. The defendant bears the burden of making good its allegation that the addition of the small amount of nitrogen did not achieve its claimed effect.

270 The defendant submits that it was obvious to add nitrogen to the synthesis atmosphere to speed up the growth of low birefringent diamonds. ¹⁷⁸ That is beside the point as it does not fully account for the inventive concept in Claim 62 of SG 872. It is undisputed that it was obvious to add nitrogen to speed up the growth of low birefringent diamonds. What is in dispute is whether it would be obvious to add nitrogen, in a controlled range, to obtain CVD diamonds of lower birefringence than those that existed in the prior art. The defendant summarises Dr Nebel’s evidence on the obviousness of Claim 62 in its closing submissions, with no less than 27 different combinations of prior art. ¹⁷⁹ They are not relevant because they are not directed at the inventive concept of Claim 62. I do not propose to analyse each combination in detail, and will analyse them under broad categories.

271 I first address the combinations which include Badzian 2000. As stated above at [241], Badzian was concerned with the growth of “nearly perfect” crystals. Although the addition of nitrogen is disclosed (without any mention of a specified range), that is in the context of “influencing step formation and eliminating of twinning”. There is nothing in Badzian 2000 which would make it obvious to the PSA to add nitrogen in the controlled range of 0.3ppm to 5ppm in order to reduce birefringence in the CVD diamond material.

272 Further, none of the prior art which Dr Nebel reads alongside Badzian 2000 render Claim 62 of SG 872 obvious. I deal with each of them briefly, save for Masahiko Mitsuhashi et al, “Dislocation of epitaxial CVD diamond and the characterization by Raman spectroscopy” (1992) 60/61 Applied Surface Science 565 (“Mitsuhashi”) and Chunlei Wang et al, “Growth and characterization of hillock-free high quality homoepitaxial diamond films” (2000) 9(9-10) Diamond and Related Materials 17650 (“Wang”), which make no reference to nitrogen concentration at all. The defendant cites Mitsuhashi for the proposition that it teaches a PSA to use a substrate with a defect density of less than 400/mm2, and Wang for the proposition that it teaches the PSA how to perform a plasma etch on the substrate to eliminate the development of hillocks.

273 According to the defendant, US 430 teaches a PSA that a CVD diamond with a nitrogen content of 0.1 to 1000ppm that is annealed will have low stress and therefore low birefringence. ¹⁸⁰ The relevant passage in US 430 reads:

274 This passage says nothing about the controlled addition of nitrogen to reduce birefringence. It only says that nitrogen may be present in the CVD diamond film. By way of a certain incorporation ratio, Dr Nebel extrapolates this to mean that nitrogen must be added in the range of 300ppb to 5ppm. In my view, there is no basis for this extrapolation. In any event, US 430 was concerned enhancing the toughness of CVD diamonds; it was not concerned with annealing to reduce the birefringence of CVD diamonds. Furthermore, Dr Nebel’s evidence in cross-examination was that annealing a CVD diamond would not reduce its birefringence: see [178] above.

275 The defendant point out that US 412 teaches a PSA that to achieve a diamond with a nitrogen content of 0.2ppm, the nitrogen in the synthesis atmosphere should be limited to 1ppm, which is within the limits of Claim 62. ¹⁸¹ There is nothing in US 412 that would even suggest adding nitrogen to reduce birefringence; in fact, as stated at [175]–[176], US 412 teaches the PSA to remove nitrogen and to limit it to no more than 1ppm.

276 The defendant contends that Bruzzi describes the diamond claimed in WO 633 and WO 634. Bruzzi discloses that such a diamond has a nitrogen content between 6ppb to 60ppb. According to the defendant, a PSA would know that this requires the diamond to be grown in a synthesis atmosphere of between 300ppb and 5ppm. However, Bruzzi does not suggest adding nitrogen to remove birefringence. The addition of nitrogen would in fact have contradicted WO 633/634 which taught the removal of nitrogen.

277 JP 890, which I have discussed in detail at [247]–[252], teaches the PSA to add a “trace amount of nitrogen” to “provide a higher quality diamond at a higher rate of synthesis”. It does not suggest to the PSA to add nitrogen to reduce the birefringence in CVD diamond.

278 Next, the defendant relies on Isberg, and combinations between Isberg and other prior art, to argue that Claim 62 of SG 872 is obvious. I do not propose to deal with each combination individually, as the respective combinations simply substitute Badzian 2000 with Isberg. The reliance on Isberg is even weaker than that of Badzian 2000 as the defendant itself acknowledges that Isberg taught the PSA to eliminate nitrogen in the synthesis atmosphere “as much as possible”. ¹⁸²

279 According to the defendant, US 021, inter alia, teaches the PSA to grow CVD diamond in an atmosphere where the concentration of the nitrogen is between 5ppm and 20ppm. The defendant then submits that by combining US 021 with other pieces of prior art (specifically, US 430, US 412, Bruzzi, or JP 890), the PSA would further limit the nitrogen range disclosed in US 021. I have dealt with these prior art above. It suffices to state that US 021, US 430, US 412, Bruzzi and JP 890 do not contain any reference to birefringence. They do not contain any suggestion that an addition of nitrogen, let alone a controlled amount of nitrogen, would reduce birefringence. I therefore do not consider that US 021 or any of its combinations renders Claim 62 of SG 872 obvious.

280 The defendant also submits that WO 633/634, read with US 430, US 412, Bruzzi and JP 890 would render Claim 62 of SG 872 obvious. To the contrary, WO 633/634 is in fact evidence of the inventiveness in Claim 62, in so far as WO 633/634 taught the PSA to remove nitrogen from the synthesis atmosphere. Page 18 of WO 633 states that:

281 Next, the defendant contends that Claim 62 of SG 872 is obvious in the light of JP 890, read with Bruzzi, Mitsuhashi, Wang, US 430 or US 412. But JP 890 is concerned with the addition of nitrogen to increase the growth rate of CVD diamonds, and Table 1 of JP 890 shows that the nitrogen has to be added at least 30ppm before the growth increase shows significant increase. In the circumstances, it does not make the teaching in Claim 62, ie the controlled addition of nitrogen within a specific range, obvious.

282 According to the defendant, Claim 62 insufficiently discloses the claimed invention. I deal with its arguments in turn.

283 First, the defendant contends that a PSA will not know how to select the appropriate nitrogen concentration because the PSA would not know the quantitative relationship between the addition of nitrogen in the synthesis atmosphere and the reduction or control of dislocation density or strain in the resulting diamond. ¹⁸³ This is wholly unmeritorious. Claim 62 itself states the nitrogen concentration to be between 300ppb and 5ppm, and that the addition of a controlled amount of nitrogen within this range, along with the other steps in Claim 62, will lead to a low birefringent CVD diamond in the SG 872 Range.

284 Second, the defendant also submits that a PSA would not be taught how to calibrate the other growth parameters to ensure that the level of nitrogen is kept consistently at the desired level of concentration during the period of growth. ¹⁸⁴ For example, while Example 1 of SG 872 discloses the pressure, temperature and gas flow rate for a process which uses 1ppm of nitrogen, it does not disclose the required geometry of the reaction chamber, the appropriate microwave power for those growth conditions or the geometry of the molybdenum substrate holder.

285 As stated at Rohm & Haas at [158], it is not sufficient for the party seeking to invalidate the patent to merely highlight ambiguities in the claims. The burden of proof is on that party “to show that those ambiguities would render the invention unworkable from the point of view of a person skilled in the art who is trying to give practical meaning to the patent specification”. In this regard, the PSA possesses common general knowledge and common sense as befits the area of technology in question. I prefer Dr Bergonzo’s evidence that the missing details, such as the geometry of the substrate holder, would be within the knowledge of the PSA skilled with working knowledge of the research and development of CVD diamond synthesis. Even if there are indeed ambiguities, as stated in First Currency Choice at [62], “it is not necessary that the specification be so detailed that this notional individual can perform the invention without any trial or experiment at all”.

286 Third, the defendant claims that Claim 62 is insufficient due to the overlap of examples in SG 872, SG 508 and GB 115 (specifically, Examples 1 and 14 of SG 872, Examples 4 and 6 of SG 508 and Examples 1 and 5 of GB 115). ¹⁸⁵ Although all the relevant examples are grown in a synthesis atmosphere where the nitrogen concentration is between 300 ppb to 5 ppm, the resulting grown diamonds have different qualities. SG 872 discloses the growth of a low birefringent diamond, SG 508 discloses the growth of a coloured diamond that is annealed into a desired colour and GB 115 claims the growth of a diamond that is coloured. ¹⁸⁶ The argument that is being run is that a PSA reading the relevant examples would expect the diamonds grown using these methods to be identical. The fact that they are not identical shows that Claim 62 is insufficiently disclosed. ¹⁸⁷

287 It is not clear how the mere fact that the examples in the three patents overlap make it such that Claim 62 of SG 872 is insufficiently disclosed. The plaintiff has explained that there are other parameters which vary between the three patents which would render the resulting material different (eg higher gas flows in SG 508 and GB 115 and higher methane concentration in SG 872 than SG 508). ¹⁸⁸ The defendant’s rebuttal is that the significance of these different parameters are not taught to the PSA in SG 872. In my view, Claim 62 of SG 872 needs to be clear and complete such that it can be performed by a PSA. Merely because the plaintiff has not stressed the significance of certain parameters which are different from other patents does not mean that Claim 62 is insufficiently disclosed. These other parameters do not constitute the inventive concept of SG 872.

288 Even if I assume that a PSA following the relevant examples in SG 508 and GB 115 would produce a low birefringent CVD within the SG 872 Range, that is a matter for the novelty and inventiveness inquiries, rather than a question of sufficiency.

289 So far as the dispute over the validity of SG 508 is concerned, the dispute centres on Claim 1 of SG 508, which the plaintiff concedes is the only independent claim of the patent. Claim 1 reads:

290 Under the “Summary of the Invention”, it is stated that the starting colour of the CVD diamond, typically brown, can upon annealing “be converted into any one of a number of desirable colours including colourless and near colourless, and particularly fancy colours [eg fancy green, fancy pink]”. The alleged invention in Claim 1 was thus particularly useful for gemstones. ¹⁸⁹

291 For reasons explained below, I find SG 508 neither novel nor inventive.

292 There is no dispute that the priority date of Claim 1 of SG 508 is 6 September 2002. ¹⁹⁰

293 In my view, Claim 1 of SG 508 lacks novelty, as it is anticipated by several pieces of prior art. It should be noted that Claim 1 is drafted in a general manner without specified parameters. So long as a prior art discloses and enables a process of annealing CVD diamonds to produce a desired colour, Claim 1 will lack novelty.

294 I begin with WO 01/72406 (“WO 406”), a patent owned by De Beers which was published on 4 October 2001 which is concerned with annealing in order to change colour. Under the heading “Description of Embodiments”, WO 406 is described as follows:

295 Claims 1 and 2 of WO 406 read as follows:

296 Based on a plain reading of Claims 1 and 2, it is clear that Claim 1 relates to brown type IIa diamonds of all origins, including CVD diamonds. As stated by Prof Newton himself: ¹⁹¹

297 The plaintiff, however, denies that WO 406 anticipates Claim 1 of SG 508. Its sole contention is that WO 406 is only concerned with natural diamonds. The example in WO 406 deals with natural diamonds and there is no mention of CVD or even synthetic diamonds anywhere in the patent. The plaintiff asserts that the defendant’s reading of WO 406 bears the hallmark of an “overmeticulous verbal analysis”. ¹⁹²

298 I reject the plaintiff’s submission. First, if one were to accept the plaintiff’s contention that Claim 1 of WO 406 is only limited in scope to natural diamonds, that essentially renders Claim 2 otiose. Second, the description of WO 406 states that the diamond will “generally be a natural diamond”. This must mean that the scope of Claim 1 of WO 406 is not restricted to natural diamonds. A PSA reading the two claims together would conclude that the method is also claimed for CVD and HPHT diamonds. In this context, this case may be distinguished from Dr Reddy, where it was held that disclosure of a large class does not result in disclosure of every member of it. In Dr Reddy, a PSA would not have inferred the specific disclosures because the claims in that case disclosed tens of thousands of chemical compounds. In the present case, a PSA reading Claims 1 and 2 would recognise that Claim 1 was also intended to cover CVD and HPHT diamonds as they were the only other categories of diamonds outside of that claimed in Claim 2. Accordingly, a PSA following the teachings in Claim 1 of WO 406 on a CVD diamond would inevitably apply the method, and achieve the result, taught in Claim 1 of SG 508. Both claims teach the PSA to anneal a diamond in order to change its colour: the difference is that Claim 1 of WO 406 refers to Type IIa diamonds (which I have found includes CVD diamonds) while Claim 1 of SG 508 refers specifically to CVD diamonds.

299 In any case, European Patent Application No 0671482A1 (“EP 482”) and United States Patent No 5451430 (“US 430”) are General Electric (“GE”) patents published in 1995 that deal specifically with CVD diamonds and reveal the same process.

300 I should first clarify that following the rule against mosaicing, I compare EP 482 and US 430 individually against SG 508. However, both parties accept that the processes described in EP 482 and US 430 are substantially similar and the reasoning below therefore applies equally to both EP 482 and US 430.

301 EP 482 describes a process where CVD diamonds could be annealed in order to reduce the size of voids and reduce strain, so as to obtain enhanced properties (optical transmission, toughness, strength, wear, uniformity of wear properties). ¹⁹³ Claim 1 of EP 482 states as follows:

302 US 430 describes a similar process of annealing in order to enhance the properties of CVD diamonds described above. Claim 1 of US 430 reads as follows:

303 In the present case, it is common ground between Prof Newton and Dr De Weerdt that the annealing process per se is substantially similar for SG 508, EP 482 and US 430. For example, there is an overlap with regard to the temperature ranges. ¹⁹⁴

304 The plaintiff’s case, however, is that both patents do not mention colour, teach annealing of a coloured CVD diamond to change its colour and/or indicate any change of colour in the CVD diamond pre- and post- annealing. ¹⁹⁵ Rather, the teaching in both EP 482 and US 430 was how CVD diamonds could be annealed to enhance its properties, and in particular, its toughness. ¹⁹⁶

305 I accept that there was no express disclosure that annealing a CVD diamond would result in a change in colour. The plaintiff is right that the colour of the CVD diamonds, let alone a change in colour, was not observed or mentioned in EP 482 and US 430. ¹⁹⁷

306  However, I consider that there is inherent disclosure in EP 482 and US 430 that a coloured CVD diamond which is annealed under suitable conditions would change to a desired colour. The plaintiff accepts that the annealing processes in EP 482, US 430 and SG 508 are, for all intents and purposes, the same. That being the case, there is no reason why a PSA, following the directions contained in EP 482 and US 430, will not inevitably apply the method taught in Claim 1 of SG 508, with the effect of producing a CVD diamond of a desired colour. As noted by Lord Hoffmann in Merrell Dow at [47], whether a PSA is working an invention is an independent fact of what he knows or thinks about what he is doing.

307 Further, as Dr De Weerdt points out, EP 482 and US 430 are concerned with improving the properties for CVD diamonds so that they could be used in applications such as laser windows and heat sinks. Such products are known to require the diamond to be colourless (in the case of laser windows) or at least near-colourless (in the case of heat sinks), which fall within the meaning of “desired colours” in Claim 1 of SG 508. ¹⁹⁸

308 That EP 482 and US 430 anticipated Claim 1 of SG 508 is also supported by the following two papers.

309 In Thomas Overton and James Shigley, “A History of Diamond Treatments” Gems & Gemology, Vol 44, No 1, pp 3235 (“Overton”), the authors stated at p 42: ¹⁹⁹

310 The second paper is authored by Dr Karl Schmetzer in 1999, titled “Clues to the Process Used by General Electric to Enhance the GE POL Diamonds” Gems & Germology, Vol 35, No 4, pp 186–190 (“Schmetzer”). ²⁰⁰ According to Schmetzer, EP 482 described a process where CVD diamonds are brought into high-pressure, high-temperature conditions. After cooling and the release of pressure, Schmetzer states that:

311 In my judgment, both Overton and Schmetzer support the fact that there was inherent disclosure in EP 482 and US 430 that annealing a CVD diamond under suitable conditions would change its colour. Claim 1 of SG 508 is therefore not novel.

312 Schmetzer itself is a prior publication that anticipates Claim 1 of SG 508. Schmetzer teaches that the original brown colour of CVD diamonds can be “removed” or “lightened” through EP 482. There is thus express disclosure of Claim 1 of SG 508.

313 The defendant contends that the focus of Schmetzer was to find out the HPHT treatments that GE had practiced or carried out on natural diamonds. That however is beside the point as it does not deal with the express disclosure in Schmetzer. In fact, the law concerning anticipation is strict to the patentee and it is immaterial if anyone knew or inspected the express disclosure in Schmetzer: Institut Pasteur at [188].

314 The effect of EP 482, US 430 and Schmetzer may be summed up in the following exchange with Prof Newton: ²⁰¹

315 Therefore the plaintiff dismisses Schmetzer as “merely speculating on unclear and/or doubtful bases”. As events unfolded, Schmetzer’s “speculation” was indeed borne out by SG 508. It was the plaintiff’s theory that annealing CVD diamonds would cause them to become darker or turn black, which I discuss below, that was speculative.

316 In any event, even if Claim 1 is novel, it fails to satisfy the inventiveness requirement.

317 To begin, the plaintiff accepts that the process of annealing would have been known to the PSA as of the priority date. SG 508 itself acknowledged that the colour of brown natural diamonds could be changed by annealing:

318 The plaintiff, however, contends that the inventiveness of SG 508 lies in the application of the process of annealing to CVD diamonds. The process of annealing per se is not inventive. This is because once the PSA learned that annealing could be done on a CVD diamond, the PSA would have “no difficulty performing the invention”, as the process of annealing was “well-known to the PSA”. ²⁰²

319 This was allegedly counter-intuitive given that the thinking as at the material time was that annealing CVD diamond would worsen its colour. Briefly, the plaintiff, relying on the evidence of Prof Newton, makes the following assertions:

(a) Prior to and as at the priority date, a PSA would know the relationship between on the one hand, defects and impurities in diamond, and on other hand, colour and annealing behaviour. ²⁰³

(b) A PSA would be aware of the different theories that explain the brown colourisation of diamonds.

(i) For natural diamonds, any brown colourisation was believed to be caused by plastic deformation of the diamond after formation by geological processes (“the plastic deformation theory”). ²⁰⁴ However, even up until today, the exact cause is not still fully understood. ²⁰⁵

(ii) For HPHT diamonds, the brown colourisation was known to be associated with higher concentrations of single substitutional nitrogen than present in CVD diamonds (“the nitrogen impurity theory”). ²⁰⁶

(iii) Neither the plastic deformation theory nor the nitrogen impurity theory could explain the brown colourisation in CVD diamonds. CVD diamonds are not exposed to conditions which can give rise to plastic deformation. Further, CVD diamonds contain less nitrogen impurities than HPHT diamonds. ²⁰⁷

(iv) Instead, the brown colourisation in CVD diamonds was believed to be caused by sp2 or non-diamond carbon defects, which are much more numerous than the quantity of nitrogen impurities typically found in CVD diamonds.

(c) Accordingly, the alleged prevailing view was that if a PSA were to anneal CVD diamonds, it would result in further degradation of the non-diamond carbon. The presence of sp2 or non-diamond carbon defects (ie, carbon that is not fully bonded) was believed to make the diamond more unstable and susceptible to conversion to graphite at higher temperatures, causing the diamond to darker or become black (“the graphitisation theory”). ²⁰⁸

(d) However, as SG 508 proved, the “deleterious effect of annealing to treat CVD diamonds to change their colour” was an “inherent misapprehension”. ²⁰⁹ SG 508 overcame a “mental prejudice” against the use of annealing for CVD diamonds to improve their colour. ²¹⁰

320 As summed up by Prof Newton, the alleged inventiveness of SG 508 was as follows: ²¹¹

321 The inventiveness of SG 508 therefore stands or falls on whether the PSA would not anneal a diamond due to concerns about it becoming darker or turning black. I reject this frame of the paradigm at the time: its sole support is Dr Newton’s unsubstantiated evidence. Instead, the prior art such as Schmetzer would have informed the PSA that annealing a CVD diamond under the suitable conditions would, as with natural and HPHT diamond, result in a change in colour.

322 I note that the plaintiff suggests that Dr De Weerdt had accepted Prof Newton’s opinion about the prevailing view, relying on the following passage. ²¹²

This does not appear to me be a clear acceptance that a PSA would refrain from annealing CVD diamond due to the possibility of it turning dark or becoming black. Dr De Weerdt’s position on the lack of inventiveness in SG 508 was clear in his AEIC and, in my view, withstood scrutiny:

323 The defendant contends that SG 508 did not teach the PSA how to anneal a diamond in order to obtain all “desired colours”, such as purple. ²¹³ In my view, the PSA would understand the phrase “desired colour” in Claim 1 of SG 508 to be limited to colours that can actually result from using annealing the CVD diamond (eg, colourless, near colourless, green, pink).

324 Next, the defendant contends that SG 508 does not teach a PSA how to calibrate the annealing conditions to achieve a specific colour. ²¹⁴ SG 508 does not contain the relevant information, such as the temperature, pressure and time, that will teach a PSA how to anneal a CVD diamond such that it changes to a desired colour. I reject the defendant’s contention. As the plaintiff points out, SG 508 contains eight examples which specify the colour of the starting diamond, the treatment(s) applied and the resulting colour. There is also discussion in SG 508 of the various colour changes achievable and the annealing conditions used. ²¹⁵ Further, this also contradicts the defendant’s case, and indeed the evidence of all the experts, that there was nothing inventive in the annealing conditions taught in SG 508. In line with my finding that a PSA would not find this novel or inventive, a PSA could easily follow SG 508 to change a CVD diamond to a desired colour.

325 I deal under this heading with a miscellany of objections that relate to but do not affect the validity of the claims which I have considered valid.

326 For SG 872, Mr Dean focused on the UK, European and Japanese patents which were derived from WO 427. He concluded that in all three jurisdictions, the product and process claims were narrower than those in SG 872. The same analysis was conducted for SG 508 and the patents in the UK, Europe and Japan which originate from WO 821.

327 In response, the plaintiff relied on the evidence of Dr Matthew Benedict David Mitchell, a qualified United Kingdom and European patent attorney who is the Senior IP Manager for the Element Six group of companies. Dr Mitchell explained that claims can be amended for a variety of reasons, and it was not unusual for the scope of a patent claim to differ from one country to another. ²¹⁶ While Dr Mitchell accepted that there were some claims in foreign jurisdictions which were narrower than SG 872 and SG 508, he highlighted that there were also other examples where the corresponding foreign patents were equivalent or broader to SG 872 and SG 508, such as in China or Israel.

328 These assertions about foreign patents are not relevant to the issue of the Singapore patents. As stated by Lord Hoffmann in Kirin-Amgen Inc and others v Hoechst Marion Roussel Limited and others [2005] RPC 169 at [35], patentees may choose to amend their proposed patents even if they disagree as to the merits of the patent examiner’s objection. It is possible that the patentee might agree to narrow the claim solely on the basis of commercial expediency.

329 Secondly, the mere fact that a foreign patent appears narrower on a literal reading does not aid the discussion. As a matter of fact, the scope of protection might still be the same if the item removed is not an “essential element of the claim” (which must be identified in order to prove infringement). It may also be narrower because of patent law. For example, the doctrine of equivalents does not apply in Singapore (see the Court of Appeal’s judgment in Lee Tat Cheng at [36]) but it does exist in jurisdictions such as the US, Japan and the UK post-Actavis UK Limited and others v Eli Lilly and Company [2017] UKSC 48.

330 Associated with this, the defendant contends that the plaintiff had a duty to ensure the patentability of SG 872 and 508, because these patents were granted under the self-assessment scheme. This contention appears to be related to and does not add anything further to the argument on foreign amendments. There was a contention that misrepresentations had been made, but no specific misrepresentation was identified or explained.

331 For SG 872, there is an additional contention under s 80(1)(e) of the Patents Act that post-grant amendments ought not to have been allowed because of substantial delay, and that this is therefore a ground for revoking SG 872. ²¹⁷ In the first place, it is unclear why any substantial delay will have the consequence of revoking the entire patent, as opposed to the amendments wrongly granted. Claim 62, as it originally stood before the amendments, would have been valid. In any event, there was also no evidence before the court to show that there was any unreasonable delay. In so far as the defendant is seeking to challenge the post-grants amendments per se, only Claim 62 is affected by this contention, and the defendant itself appears to be out of time to make an objection.

332 The trial focused on primarily three claims, Claims 1 and 62 of SG 872, and Claim 1 of SG 508. The defendant characterises Claim 1 of SG 872 and Claim 1 of SG 508 as invalid independent claims, and relies on the Court of Appeal’s decision in Sunseap Group Pte Ltd and others v Sun Electric Pte Ltd [2019] 1 SLR 645 (“Sunseap”) at [70] for the proposition that “[i]f the court finds in the defendant’s favour that the independent claims are invalid, it follows that the dependent claims must also fall”. ²¹⁸

333 In respect of SG 872, I have decided that Claims 1 and 62 are valid. As such, Sunseap is distinguishable in the present case.

334 I should mention that the plaintiff appears to accept in its closing submissions that the independent claims of SG 872 are Claims 1(ii) and (iii) only, drawing a distinction with independently valid claims, of which Claim 62 is one. ²¹⁹ The distinction in nomenclature was not defined in the submissions nor in the pleadings, although in a 13 August 2015 letter to the Intellectual Property Office of Singapore the plaintiff contended that “[t]he independent method Claim 62 has … been made dependent upon producing the material of any of Claim 1 and the dependent product claims”. ²²⁰ As Wei J noted at [103] of Lee Tat Cheng v Maka GPS Technologies Pte Ltd [2018] 3 SLR 1334 (“Lee Tat Cheng (HC)”), these terms, such as independent and dependent claims, do not appear in the legislation, and at [104], such terms “should not distract the court from the enquiry which it is tasked to undertake, which is whether the elements or features in the subsequent claim(s) taken together with the invention as set out in the preceding claim meet the requirements of novelty.” Claim 62 stands alone as the main process claim of SG 872, to which Claims 63-71 add features. It does not add to or limit Claim 1. An assumption that Claims 62 and 1 could be distinctly delineated from each other and have separate potentially inventive concepts appears also to have been made by the experts and parties at trial, and I have proceeded on this basis. In addition, I held at [220] that Claims 57-58 reflect new distinguishing features to the product in SG 872. In Lee Tat Cheng (HC) at [104], which the Court of Appeal in Sunseap referenced specifically at [70], Wei J accepted that features in a subsequent claim, taken together with the invention as set out in a preceding claim, could meet the requirements of novelty. My holding in respect of Claims 57-58 is on this basis.

335 In respect of SG 508, I have decided that Claim 1 is invalid. The plaintiff’s entire case regarding the inventiveness of SG 508 rests on the concept of applying annealing to CVD diamonds. The other dependent claims asserted are in respect of the nitrogen concentration of the annealed diamond (Claims 8-10, 12-14), colour of the annealed diamond (Claims 18, 24-25), reduction/removal of the absorption band in the annealed diamond (Claim 41) and the temperature ranges of the annealing process (Claim 44-45). ²²¹ This is the scenario Sunseap at [70] is targeted towards. In my judgment, these features would lack novelty and/or inventiveness when read together with Claim 1. This is unlike Claims 57 and 58 of SG 872, where even if low birefringent CVD diamonds in the SG 872 range existed, the product described in Claims 57 and 58 could still have been patentable (ie, low birefringent CVD diamonds with a higher nitrogen content than the prior art given the deliberate addition of nitrogen taught in SG 872).

336 Aside from copies released to the confidentiality club, parts of this judgment that reveal the defendant’s confidential process have been redacted and are represented by [square brackets] below.

337 For the purposes of proving infringement, the plaintiff relies on three samples: Sample 2, Sample 3 and Sample 4 (collectively, “the Samples”). Each of the Samples were shipped to (or in the case of Sample 3, brought to) and centrally held at the De Beers Technical UK facility in Maidenhead (“the Maidenhead Facility”). ²²² When Samples 2, 3 and 4 arrived at the Maidenhead Facility, they were marked “NL625-03”, “NL702” and “NL719-06” respectively. ²²³ The Samples were kept in a specially secured room, known as the Strong Room, unless they were taken out for DiamondView fingerprinting or internal/external tests to test for infringement. The fingerprints here refer to the various DiamondView images, cross-polarised images and weights and dimensions of the Samples which go towards showing that there was no break in the chain of custody of the Samples. The internal tests were conducted in-house by various scientists and technicians employed by De Beers UK Limited. The external tests were conducted by Dr Steven Huband and Dr Ben Breeze at the University of Warwick and by Lazer Zentrum Hannoever e.V. (“LZH”). ²²⁴ The movements of the Samples in and out of the Strong Room were recorded in daily checkout lists (“DCL”). It is the plaintiff’s case that the fingerprints, along with the DCLs and other contemporaneous documents, demonstrate that the Samples were properly tracked, handled and fully accounted for at all material times. ²²⁵

338 The defendant denies that the Samples originated from it. Further, the defendant also claims that the plaintiff has not proven an unbroken chain of custody for the Samples. ²²⁶

339 As I explain below, I find the defendant’s contentions on provenance and chain of custody to be wholly without merit. Some of the propositions advanced were based on principles from criminal law which, as I shall explain, should have no applicability in civil cases. Serious allegations such as evidence tampering and witness collusion were also made without any regard to the strength and cogency of the evidence nor the fact that the law requires compelling evidence where such allegations are made (see Tang Yoke Kheng (trading as Niklex Supply Co) v Lek Benedict and others [2005] 3 SLR(R) 265 at [14]).

340 I first address the applicable principles on provenance.

341 In order for the plaintiff to succeed on infringement, it must prove that infringing Samples originated from the defendant. Parties do not dispute guidance given by the Court of Appeal in Britestone Pte Ltd v Smith & Associates Far East, Ltd [2007] 4 SLR(R) 855 at [60]:

342 A recurring argument made by the defendant is that there is “a need for persons with personal knowledge to testify to the alleged provenance”. This is “especially when it relates to the selection and handling of samples that are the subject of experiments and when the case turns on the experiments conducted on the samples”. ²²⁷ In support of this proposition, the defendant cites several cases which I discuss briefly. In my view, none of these cases stand for the proposition that in order to prove provenance, the plaintiff must call persons with personal knowledge to testify. There is nothing to prevent the plaintiff from adducing other evidence, including documentary evidence, to prove the provenance of the Samples.

343 In Alliance Management SA v Pendleton Lane P and another and another suit [2008] 4 SLR(R) 1 (“Alliance Management”), a court order was made for the defendants to produce and return by a stipulated date an original hard disk (“the Hard Disk Order”). The purpose of the Hard Disk Order was to facilitate discovery and production for inspection of certain electronic documents stored in the hard disk. The defendant failed to comply with the Hard Disk Order. On that basis, the plaintiff applied to strike out the defence: Alliance Management at [1]–[3].

344 Belinda Ang Saw Ean J held that there was a deliberate and persistent disregard of the Hard Disk Order and that such conduct fell within the category of contumelious conduct justifying a striking out of the defence: Alliance Management at [28].

345 For present purposes, it is relevant to note that Ang J was prepared to consider the fact that the defendants had allegedly produced a clone of the hard disk (“the Hitachi hard disk”) as part of the overall circumstances the court would consider in exercising its discretion to strike out the defence. The Hitachi hard disk was said to be sent to the first defendant in October 2005 by one Ms Joseph. However, in the hard disk that was produced in court (which was said to be the Hitachi hard disk), the manufacturer’s label and warranty label indicated that it was manufactured in November 2005 and sold in December 2005. Under those circumstances, Ang J held that “the provenance of the Hitachi hard disk had not been made out and remained dubious”: Alliance Management at [36]–[40].

346 It is unclear how the defendant derives, from Alliance Management, the proposition that there is a need for persons with personal knowledge to testify as to provenance. In Alliance Management, the reason why the provenance of the Hitachi hard disk was not made out was because the dates on it which it was manufactured and sold contradicted the first defendant’s account of when he obtained the Hitachi hard disk. There were glaring inconsistencies which could not be explained. It was not because Ms Joseph, who provided the Hitachi hard disk to the first defendant, had failed to testify.

347 Next, in Kalzip Asia Pte Ltd v BFG International Ltd [2018] SGHC 152 (“Kalzip”), there was a dispute between the plaintiff contractor and the defendant sub-contractor over alleged defects in roof panels that had been installed in a development. The panels were constructed of glass fibre-reinforced skins that enveloped an aluminium honeycomb. The dispute concerned whether and to what extent the inner skins of the panels had “delaminated” (ie, come apart) from the aluminium honeycomb and whether the panels met the fire safety requirements of the contract: Kalzip at [1].

348 The defendant relied on representative samples derived from panels produced in 2010 (the relevant date) to prove that the panels complied with the contractual specifications. The plaintiff casted doubt on the provenance of the panels. It alleged that the defendant’s expert, Mr Wymond, did not personally investigate the provenance of the panels and appears to have accepted from photographs showing tag markings of the panels that they were panels from 2010. Quentin Loh J rejected the plaintiff’s contention. He noted that another of the defendant’s expert, Mr Maurieschat, had confirmed that he had visited the defendant’s facility before the preparation of the samples and “personally saw those panels onsite labelled with their production notes”: Kalzip at [187]–[188]. The defendant in the present case claims that implicit in Loh J’s reasoning was that “if a claimant fails to call a witness to personally identify and account for a sample, the Court should not accept the claimant’s case on provenance”. ²²⁸

349 I see no merit to this contention. It appears to me that Loh J was not making a general proposition that a party must call a witness to personally identify and account for a sample if it seeks to rely on it. Loh J had simply found, on the facts of Kalzip, that the defendant had satisfied its burden of showing provenance.

350 Finally, the defendant relies on the case of Contour Optik Inc and others v Pearl’s Optical Co Pte Ltd and another [2002] SGHC 238 (“Contour Optik”). There, the plaintiff sued the defendants for patent infringement, with the relevant patents being in respect of spectacle frames. The plaintiff trap purchased several spectacles frames from the defendants. Lee Seiu Kin JC (as he then was) held that while the plaintiff had called expert witnesses to give evidence on spectacle frames alleged to be the trap purchase, they did not call the person who made the trap purchase, or anyone who may have witnessed it, to identify an exhibit as the trap purchase. The plaintiff’s case therefore failed on the basis due to the “break in the chain of evidence”: Contour Optik at [52]–[53], [83], [85].

351 Contour Optik is distinguishable. It appears that there was no other evidence, such as documentary evidence, in Contour Optik which could have identified the provenance of the spectacle frames in that case. In fact, one might perhaps be able to place greater weight on contemporaneous documentary evidence, as opposed to witness testimony, in cases such as the present when the relevant samples are not identifiable by naked eye inspection alone. ²²⁹

352 The plaintiff accepts that it has the burden of proof in respect of proving the chain of custody of the samples. In this context, I am of the view that it suffices for the plaintiff to prove that it is more likely than not that the samples remained the same between the time they were purchased from the defendants and underwent the relevant tests. ²³⁰

353 According to the defendant, “a break in the chain [of custody] or a movement or handling that is not accounted for is fatal to the claimant’s case. Each link, movement or handling of each of the Samples in the chain must be accounted for by admissible evidence”. ²³¹ However, I am not satisfied that this proposition is borne out by the cases relied on by the defendant, whereby the court declined to rely on evidence on the basis of a break of chain in custody.

354 First, in Ecooils Sdn Bhd v Raghunath Ramaiah Kandikeri [2014] 7 MLJ 44 (“Ecooils”), the plaintiff commenced an action against the defendant arising from the defendant’s breach of the terms of a confidentiality clause in his letter of appointment. The plaintiff led forensic evidence of documents and emails contained in the defendant’s computer. The defendant challenged the plaintiff’s forensic evidence, with one of the grounds being that there was no evidence in respect of the chain of custody, care, control and usage of the computer from the date the defendant left the employment of the plaintiff until it was handed over for forensic examination. The relevant time period was almost three years. It was held that “[t]he plaintiffs did not make any attempt to adduce any evidence of the proper measures or procedures adopted to secure [the computer’s] integrity” during that period: Ecooils at [62]–[63].

355 In my view, Ecooils does not stand for the proposition that “[e]ach link, movement or handling of each of the Samples in the chain must be accounted for by admissible evidence”. In fact, Ecooils suggests that it suffices for the plaintiff to adduce evidence of the proper measures or procedures adopted to secure the chain of custody of the Samples. Ecooils ought also to be seen in the context of the three years gap between the date the defendant left the plaintiff’s employment and the forensic examination.

356 Next, in Exim & Manufacturing Holdings Pte Ltd v Fintex Industries Pte Ltd [2007] SGHC 220 (“Exim”), the plaintiff sued the defendant for breach of contract; specifically, it was alleged that the defendant had failed to “bake” screws according to specification. The plaintiff relied on experiments conducted by its expert, Dr Huang on the screws. Lee Seiu Kin J held that the plaintiff had not proven, on a balance of probabilities, that the defendant had not properly baked the screws on the basis of Dr Huang’s evidence. A reason, at [27], was that the plaintiff had not proven the chain of custody in respect of the samples sent to Dr Huang for testing. But nowhere in Exim does it state that the plaintiff must account for “[e]ach link, movement or handling of each of the Samples”, and that a failure to do so will be “fatal” to the plaintiff’s case. ²³²

357 Finally, I turn to the case of Mohamed Affandi bin Rosli v Public Prosecutor and another appeal [2019] 1 SLR 440 (“Affandi”). According to the defendant, Affandi stands for the principle that if there is a doubt as to the identity of an exhibit, then every single witness who handled the exhibit must be called to establish the chain of custody. ²³³

358 In Affandi, the question was whether the drug samples tested by the Health Sciences Authority were the same samples seized from the accused. The Court of Appeal made the observation at [39]–[42] that it is incumbent upon the prosecution in such cases to account for the movement of exhibits from the point of seizure to the point of analysis.

359 Affandi ought to be seen in its context as a criminal case, where the burden is on the Prosecution to prove beyond a reasonable doubt that the relevant exhibits were the ones seized from the accused, and there is an unbroken chain of custody. In the context of civil cases, the standard is that of a balance of probabilities: Chua Kwee Chen v Koh Choon Chin at [13]. The plaintiff only has to show, on a balance of probabilities, that the samples which were tested and shown to be infringing were the same samples which originated from the defendant.

360 I would conclude that it should be noted from Affandi that even in the criminal context, the court will not entertain “speculative arguments” about the possibility of a break in the chain of custody: Affandi at [41]. The defendant must raise a reasonable doubt or suspicion; it cannot sit on its heels and demand that the plaintiff prove every movement of the exhibit in question. In my judgment, the defendant’s contentions, to a large extent, were founded purely on the theoretical possibility of a break in the chain of custody.

361 Sample 2 is an optical grade single crystal CVD diamond plate with the product code 2PCVD303004N purchased by Dr Jarmola from MWE, on behalf of the plaintiff under instructions from Dr Twitchen on or around 12 May 2014.

362 The defendant accepts that it sold to MWE 20 diamond plates with the product code 2PCVD303004N. ²³⁴ However, it disputes the plaintiff’s claim that MWE then on-sold the 20 plates to Dr Andrey Jarmola from the University of California, Berkeley (“UC Berkeley”). Further, it also disputes the plaintiff’s claim that the 10 plates which Dr Jarmola sent to Dr Twitchen were the same plates that Dr Jarmola had received from MWE.

363 In my judgment, the plaintiff has established, on a balance of probabilities, that Sample 2 originated from the defendant. I place reliance on the contemporaneous documentary records, which are admissible pursuant to s 32(1)(b)(iv) of the Evidence Act (Cap 97, 1997 Rev Ed) (“Evidence Act”) which states as follows:

364 The quotation issued by the defendant to MWE (“the IIa-MWE Quotation”) ²³⁵ and the quotation issued by MWE to Dr Jarmola (“the MWE-Dr Jarmola Quotation”) ²³⁶ are highly probative of the fact that the diamond plates sold by the defendant to MWE were the same diamond plates on-sold and delivered to Dr Jarmola.

365 The defendant issued a sales quotation with Quotation No IIa/QT/1314-121 dated 21 February 2014 to MWE for lab grown diamond plates. The item code on the quotation, 2PCVD303004N is identical to the product code for Sample 2. While I note the defendant’s point that the product code 2PCVD303004N is a common notation not unique to diamond plates grown by the defendant, ²³⁷ there are other factors which put beyond doubt the provenance of Sample 2.

366 First, UC Berkeley was indicated on the IIa-MWE Quotation below MWE’s address. In cross-examination, Mr Mehta accepted that the defendant knew that “someone had communicated to IIa that there was a customer from UC Berkeley that wanted to buy certain plates and, hence those words appear in this quote to MWE”. ²³⁸

367 Second, three days after the IIa-MWE Quotation was issued, MWE issued a corresponding quotation dated 24 February 2014 to Dr Jarmola of UC Berkeley. The MWE-Dr Jarmola Quotation explicitly states that “the following quotation is for Lab Grown, CVD single crystal diamond plates, produced by IIa Technologies Pte LTD …”. The MWE-Dr Jarmola Quotation references the IIa-MWE Quotation, 1314-121. The same items are listed with precisely the same product/item codes, product descriptions and unit prices. Curiously, the MWE-Dr Jarmola Quotation also makes reference to “GST @0%” when no tax of the same title or abbreviation is imposed in the US. It appears that the MWE-Dr Jarmola Quotation had simply adopted this from the IIa-MWE Quotation. ²³⁹

368 Against the IIa-MWE Quotation, MWE issued a purchase order dated 7 May 2014 to the defendant for the production and shipment of, amongst others, 20 pieces of diamond plates with the Item Code 2PCVD303004N at a unit cost of US$101.00. Reference is made to the IIa-MWE Quotation, 1341-121, and the customer, UC Berkeley. A 10% distributor discount was also reflected on the MWE-IIa Purchase Order, which suggests the existence of a distributorship arrangement between MWE and the defendant.

369 Next, I turn to the invoices issued by MWE and the defendant respectively. MWE issued an invoice dated 12 May 2014 to Dr Jarmola (“the MWE Invoice”) for, amongst other things, the same 20 pieces of diamond plates with the Item Code 2PCVD303004N at a unit price of US$101.00. The plates were to be shipped to UC Berkeley.

370 The defendant then issued an invoice dated 6 June 2014 to MWE (“the IIa Invoice”). The invoice was for 20 pieces of diamond plates with the Item Code 2PCVD303004N at a unit price of US$101.00. The country of origin was stated to be Singapore. The IIa Invoice also stated the customer reference as UC Berkeley. The total carat weight for the 20 pieces of diamond plates was 2.12.

371 On 9 June 2014, MWE issued a packing slip further to the MWE Invoice, which provided for delivery of 20 pieces of diamond plates with the Item Code 2PCVD303004N at a unit price of US$101, and a total weight of 2.12.

372 I find that the contemporaneous business records alone sufficiently prove that the diamond plates sold by the defendant to MWE were the same plates on-sold to Dr Jarmola. It would be wholly speculative to then suggest that Dr Jarmola tampered with or mishandled the glass plates before sending it to Dr Twitchen. The defendant’s contention that the plaintiff was required to call a representative from MWE and Dr Jarmola himself is wholly unsustainable. ²⁴⁰ Accordingly, I find that the provenance of Sample 2 is established on a balance of probabilities.

373 For completeness, I note that the plaintiff contends that the evidence shows an exclusive supply relationship between the defendant and MWE. ²⁴¹

374 The plaintiff relies on various Internet articles and presentations to prove an exclusive supply relationship between the defendant and MWE. However, on this point, I am inclined to agree with the defendant that these articles and presentations are inadmissible hearsay evidence. In Clark Jonathan Michael v Lee Khee Chung [2010] 1 SLR 209 (“Clark Jonathan Michael”), the plaintiff had claimed against the defendant for loss of income. He had quantified this claim at $93,085.00 on the basis that a staff nurse in Portland, Oregon (where he would have worked at) would have earned this amount during the relevant period of time. In support of this amount, the plaintiff relied, inter alia, on statistics compiled by an online website known as “salary.com”: Clark Jonathan Michael at [61]. Judith Prakash J (as she then was) refused to make an award for loss of income. On the statistics compiled on “salary.com”, Prakash J held that such evidence was inadmissible hearsay evidence: Clark Jonathan Michael at [70]. I therefore do not place weight on this aspect of the evidence in determining that Sample 2 originated from the defendant.

375 The defendant in any event accepts that the MWE is one of its distributors, ²⁴² although there have been no orders since 2017. ²⁴³ Mr Mehta gave evidence that he was told by Mr Richard Garard of MWE that MWE also purchases diamonds from “other growers”. This relationship, taken with the documentary evidence, is sufficient to prove that Sample 2 originated from the defendant.

376 I deal now with a point made by the defendant relating to the dimensions of the diamond plates which in its view, suggests that the diamond plates did not originate from it.

377 The defendant points out that according to the quotations and invoices, the diamond plates had dimensions of 3.0mm x 3.0mm x 0.4mm. However, when the Maidenhead Facility received the 10 diamond plates from Dr Twitchen, which were then measured by Dr Cann, the dimensions of the plates differed from 3.0mm x 3.0mm x 0.4mm. For example, according to an email from Dr Cann to one Ms Ford dated 26 June 2014, Sample 2 measured 3.04mm x 3.26mm x 0.73mm. ²⁴⁴

378 I see no merit in the defendant’s contention. Ms Susan Jane Fletcher Watts, the plaintiff’s principal factual witness who is presently a consultant patent attorney for the plaintiff and its former head of intellectual property, gave evidence that the diamond plates that were delivered were thicker than its thickness stated on the invoice. ²⁴⁵ It is “quite normal” for the diamonds received to not meet the precise specifications. ²⁴⁶ To this end, the plaintiff disclosed on 22 March 2019 an email which sets out the measurements of all 10 diamond plates that Dr Twitchen sent to the Maidenhead Facility. ²⁴⁷ All 10 plates had variations in dimensions in spite of their quoted dimensions. Further, the plaintiff also points out that if the 20 diamond plates had exact dimensions of 3.0mm x 3.0mm x 0.4mm, the carat weight would not have been 2.12 carats, which was the actual carat weight listed by the defendant in its invoice and by MWE in its packing slip to Dr Jarmola. ²⁴⁸ I note that similar arguments relating to dimensions were made for the other samples and my finding here applies equally to those contentions. Ultimately, these differences in dimensions are in the region of sub-millimetres, and one should also note that the lack of precision in measurements could also be due to the inherent margins of error of the measurement tools (ie Vernier callipers and weighing scales). ²⁴⁹

379 Finally, I note that it was always open to the defendant to inspect and examine the Samples and adduce positive evidence as to why the Samples did not originate from it. ²⁵⁰ Instead, the defendant criticised the plaintiff for not bringing the Samples to court and chose to speculate on holes in the plaintiff’s account of the provenance and chain of custody of the Samples. In my view, this reflects an incorrect understanding of the burden of proof.

380 Sample 3 is a single crystal CVD diamond gemstone with product code LG10225420 purchased by Dr Lawson, on behalf of the plaintiff, from PGD on or around 27 October 2015. In cross-examination, Dr Lawson explained that he had selected the stones on PGD’s website, and then called his wife, Mrs Ayako Lawson to carry out the actual transaction. He was concerned that given his profile in the field, the sale might have been refused. ²⁵¹

381 That Sample 3 was obtained from PGD is confirmed by various documents, including an invoice, commercial invoice, packing list, FedEx shipment document and a report from the International Gemological Institute No LG10226420 dated 18 June 2015. ²⁵²

382 The more pertinent question is whether Sample 3, which was sold by PGD, was in turn obtained from the defendant. In my view, the plaintiff has established on a balance of probabilities that Sample 3 originated from the defendant.

383 It ought to be highlighted that at all material times, both the defendant and PGD were owned by IIa Holdings Group Ltd. ²⁵³ In turn, IIa Holdings Group Ltd is owned by members of the Mehta family. ²⁵⁴ I accept that the common ownership of PGD and the defendant, in and of itself, does not mean that PGD could not obtain diamonds from other sources. However, this has to be coupled with the fact that Mr Mehta, who is presently the sole shareholder of PGD, was in a position to have PGD produce documents showing that the documents that were sold to Dr Lawson were obtained from other sources instead of the defendant. Mr Mehta confirmed this in cross-examination. ²⁵⁵ Under these circumstances, it seems to me appropriate to draw the inference that the production of the documents would have showed that Sample 3 originated from the defendant. On a balance of probabilities, I accept the plaintiff’s contention that Sample 3 originated from the defendant.

384 For completeness, I note that so far as Sample 3 is concerned, the plaintiff also relies on various Internet articles to prove an exclusive supply relationship between PGD and the defendant. Some of these articles, such as a web article from www.prnewswire.com, constitutes inadmissible hearsay evidence. Others, such as a news release on the defendant’s own website only goes towards showing a supply relationship between PGD and the defendant, rather than an exclusive supply relationship. ²⁵⁶ That the defendant actively advertises for PGD on its Facebook page also does not, in and of itself, suggest an exclusive supply relationship. ²⁵⁷

385 On the provenance of Sample 3, the defendant raises several arguments which in my view, do not go towards showing that Sample 3 did not originate from the defendant. For example, the defendant observes that the commercial invoice from PGD states that the Country of Origin of the diamond listed is China. ²⁵⁸ I accept the plaintiff’s explanation that this could equally mean that Sample 3 had passed through certain manufacturing processes (such as cutting and polishing) in China, or that the relevant supply chains from the defendant to PGD passed through China. If indeed the origin of Sample 3 was a diamond supplier in China, Mr Mehta was in a position, as majority shareholder of PGD, to produce the identity of the relevant diamond supplier with the necessary supporting documents.

386 Sample 4 is an optical grade single crystal CVD diamond plate with the product code 2PCVD505005N purchased by Mr Pierra on behalf of the plaintiff directly from the defendant in Singapore in or around October 2015.

387 Mr Pierra was subpoenaed by the plaintiff. At trial, the defendant agreed to admit his evidence in his affidavit without any cross-examination. Under those circumstances, Mr Pierra’s evidence that he purchased Sample 4 from the defendant and shipped it to the plaintiff remains unchallenged. ²⁵⁹

388 Further, Mr Pierra had also liaised directly with Ms Lin Lin, the defendant’s technical marketing engineer at the material time. ²⁶⁰ The contemporaneous business records show clearly too that Sample 4 originated from the defendant, these being a quotation dated 23 October 2015, a tax invoice dated on 8 January 2016, and a delivery order dated 8 January 2016. All three documents were issued by the defendant and the latter two documents were acknowledged by Mr Pierra by signature.

389 Accordingly, the plaintiff has proven that Sample 4 originated from the defendant on a balance of probabilities.

390 I deal briefly with whether there has been a break in the chain of custody. In my view, the plaintiff, having established that the three Samples originated from the defendant, need only prove, on a balance of probabilities, that these were the very samples tested for infringement. In the present case, the evidence of the fingerprints, along with the “traceability” system at the Maidenhead Facility render the possibility of confusion, misplacement or replacement of diamond samples no more than a theoretical one raised by the defendant.

391 In order to prove the chain of custody of the Samples, the plaintiff relies on Dr Martineau’s evidence in respect of the fingerprints of the Samples. Essentially, Dr Martineau compared the DiamondView images, cross polarised images, weights and dimensions taken of the Samples at various stages. Collectively, these served as fingerprints showing that the same Samples moved along the chain of custody. ²⁶¹

392 DiamondView images are taken using the DiamondView machine which is commercially available. It is, as Dr De Weerdt accepted, a reliable method for identifying CVD diamonds. ²⁶² Dr Martineau explained the operation of the DiamondView machine in the following terms: ²⁶³

393 The evidence of the DiamondView images for the Samples can be summarised as follows: ²⁶⁴

(a) Sample 2: DiamondView images were taken on 2 July 2014, 22 December 2015 and 16 January 2017. By the last date, all the relevant tests for the purposes of proving infringement had been carried out. In all three DiamondView images, Dr Martineau observed that there was a pattern of blue fluorescence along one edge (the lower edge) of the image. Further, that the image on 16 January 2017 showed predominantly orange luminescence was evidence that Sample 2 was in the same state in which it was purchased.

(b) Sample 3: DiamondView images were taken on Sample 3 on 26 November 2015, 14 December 2015 and 22 December 2015 respectively. In all DiamondView three images, Dr Martineau observed that there were distinctive patterns of green luminescence due to the formation of H3 defects following annealing of Sample 3.

(c) Sample 4: Three DiamondView images were adduced for Sample 4 dated 20 January 2016, 18 February 2016 and 16 January 2017. By the last date, all the relevant tests for the purposes of proving infringement had been carried out. In all three images, there were distinctive patterns of orange luminescence.

394 The dates in which the DiamondView images were taken are pertinent, as they put to rest many of the defendant’s unsubstantiated allegations that there must have been a break in the chain of custody because the plaintiff failed to account for the movement of a sample on a given date. While I accept that the fingerprints do not track “each and every moment” of the Samples, they show, at least for the relevant dates concerned, that many of the defendant’s arguments were advanced without regard to the strength or cogency of the evidence adduced.

395 Cross-polar images were also taken of the Samples on various occasions. For example, cross-polar images were taken of Sample 2 on 23 June 2014. Dr Martineau highlighted that they showed “distinctive patterns of contrast” which were unique to Sample 2. These patterns of contrast were closely linked to the stitched Metripol image taken on 5 December 2015. Dr Martineau’s evidence was that the various cross-polar images were from the same sample: “I can say categorically that there’s no way that you can reproduce the level of detail, the spatial distribution of those strain-causing defects in a separate sample. That is just beyond the bounds of possibility.” ²⁶⁵ It should be noted that Dr Kaminsky had also candidly accepted in cross-examination that his personal opinion was that the cross-polarised images for Sample 2 were all of the same sample. ²⁶⁶

396 The weight and dimensions of the Samples were also recorded at various dates, therefore serving as fingerprints of the Samples along the chain of custody. For Sample 2, the following measurements were recorded:

(a) 4 December 2015 (while Sample 2 was at Warwick for Metripol testing): 0.025g, 3.04mm x 3.23mm

(b) 9 December 2015 (at Warwick, prior to return of Sample 2 to the Maidenhead Facility): 0.025g, 3.02mm x 3.24mm

(c) 21 March 2016 (while Sample 2 was at Warwick for Metripol testing): 0.025g, 3.02mm x 3.24mm x 0.73mm

(d) 24 November 2016 (while Sample 2 was at Warwick for Metripol testing): 0.024g, 3.01mm x 3.22mm x 0.74mm

397 Dr Martineau concluded that the weights and dimensions above were in “reasonable agreement”, and reasoned as follows: ²⁶⁷

398 The defendant raises several general objections against the use of these fingerprints. First, the defendant points out that Dr Martineau admitted that the plaintiff does not have a “fixed protocol” for fingerprinting. ²⁶⁸ This misses the point, which is whether the relevant fingerprints adduced by the plaintiff show that there was an unbroken chain of custody for the Samples, on a balance of probabilities. Next, the defendant contends that Dr Martineau’s evidence constituted opinion evidence and was inadmissible, as he was called as a factual witness. Second, Dr Martineau was also not involved in the experiments or measurements of the fingerprints. ²⁶⁹ It appears to me, however, that the various fingerprints are admissible as statements made in the ordinary course of trade under s 32(b)(iv) of the Evidence Act. Further, it would also not be correct to suggest that Dr Martineau’s evidence was entirely opinion evidence as he had working knowledge of the DiamondView (see Jeffrey Pinsler, SC, Evidence and the Litigation Process (LexisNexis, 6th Ed, 2017) at 8.005: “the law takes a pragmatic approach by classifying direct perception of something that can be seen or heard (or directly perceived by some other sense) as evidence of a fact.”) In providing his observations of, for instance, the pattern of blue fluorescence in the DiamondView images, Dr Martineau was providing factual evidence. While he went further to draw inferences based on these observations, for example, that they related to the same Sample, it ought to be recalled that Dr Martineau, while called as a factual witness, was, for all intents and purposes, an expert in CVD diamond. In this regard, I draw guidance from Tan Siong Thye J’s caution in Goh Guan Sin (by her litigation representative Chiam Yu Zhu) v Yeo Tseng Tsai and another [2019] SGHC 274 at [97]–[101] that factual witnesses with the requisite experience and knowledge may be able to give relevant expert evidence. Such evidence should be considered with other expert evidence before appropriate weightage is given.

399 I come therefore to the evidence of Dr Nebel, who stated that “[n]on-experts cannot perform fingerprinting, and even if it is performed by experts, it is highly unreliable and can be manipulated by image processing”. ²⁷⁰ Dr Nebel’s opinion did not carry robust reasoning, and was an isolated one. Even the defendant’s own expert, Dr De Weerdt, had stated that if a PSA were to apply DiamondView, it would be a reliable method for identifying CVD diamonds. I therefore hold that the collective measures of fingerprinting, which included DiamondView, are sufficiently reliable.

400 It follows from my acceptance of the fingerprinting, and in particular, DiamondView, evidence that there is no argument against Samples 2 and 4. It is only for Sample 3, for which birefringence measurements were taken at LZH and the University of Warwick after DiamondView images were taken, that any dispute remains. I deal, in this context, with the defendant’s contentions regarding such external sources of testing.

401 The defendant protests that the Samples were tested at Warwick and LZH. However, no one from Warwick or LZH was called to give evidence on how the Samples were handled when they were at Warwick or LZH for testing. ²⁷¹ While Ms Watts had provided explanations of how Warwick and LZH handed the Samples, she was not an employee of Warwick or LZH and was not in a position to give any evidence on the procedures adopted by them. ²⁷² But as stated above, it is not necessary for each and every single individual involved in the chain of custody to give evidence on behalf of the plaintiff. The defendant’s bare assertion that there might have been a break in the chain of custody while the Samples were sent for testing at these external institutions is speculative.

402 The same reasoning applies to the individuals who were tasked to send the Samples to the external facilities. For example, the defendant points out that while Ms Watts had handled Sample 2 to Mr Ian Friel so that it could be sent to LZH, Mr Friel did not give evidence. ²⁷³ In so far as there were shipping records proving that Mr Friel sent Sample 2 to LZH, that was inadmissible as they were not produced in the ordinary course of business. ²⁷⁴ Be that as it may, and contrary to what the defendant suggests, the mere fact that “there is no evidence to account for what happened to Sample 2” does not amount to a break in the chain of custody. ²⁷⁵ It still remains only a theoretical possibility that there would have been a break in the chain of custody in the intervening period between Mr Friel receiving Sample 2 and sending it to LZH.

403 I conclude therefore, that Sample 3, as tested at LZH and Warwick, is the same sample which originated from the defendant.

404 For completeness, I deal with the plaintiff’s traceability system, only because much trial time was consumed by the defendant on this issue. Ms Watts’ gave evidence as to the “traceability” system established at the Maidenhead Facility. She explained as follows in her AEIC: ²⁷⁶

405 In my view, the traceability system lends weight to the fact that there was no break in the chain of custody. It represented a proper system designed to ensure the integrity of the Samples while at the Maidenhead Facility. The fact that the system does not provide for a “perfect chain of documentation” is beside the point. ²⁷⁷

406 The plaintiff relies on s 32(1)(b)(iv) of the Evidence Act to admit the DCLs, on the basis that these are documents made in the course of business. Nevertheless, the defendant contends that the court should exercise its discretion to exclude the evidence under s 32(3) of the Evidence Act, on the basis that the DCLs are “fraught with inconsistencies and suspicious corrections”. In this connection, the guiding principle for when s 32(3) ought to be exercised was set out by the Court of Appeal in Gimpex at [109]:

407 I disagree with the defendant that the DCLs were fraught with inconsistencies and suspicious corrections. In my judgment, the inconsistencies could be explained innocently or were simply administrative errors, as I explain below. Similarly, there was nothing sinister about the corrections or amendments made to the DCLs. I therefore decline to exercise s 32(3) of the Evidence Act to exclude the evidence.

408 The defendant asserts that the plaintiff ought to have put forward a witness who had personal knowledge of the ‘traceability’ system. ²⁷⁸ In particular, “the person who was in charge of the ‘traceability’ system … would have been a more appropriate witness”. ²⁷⁹ Ms Watts is not and never was an employee of the Maidenhead Facility. She was not involved in the filling up of the DCLs. In my view, Ms Watts’ knowledge of the traceability system was derived from her visits to the Maidenhead Facility, and her evidence on the system was also supported by Dr Lawson, who is an employee of the plaintiff. ²⁸⁰ In any event, the DCLs, as admissible evidence under the business records exception to the hearsay rule, speak for themselves.

409 I do not consider it necessary to go through all the various alleged inconsistencies and discrepancies identified by the defendant in respect of the traceability system. Instead, I highlight certain types of arguments that were made by the defendant, and explain why I find them to be without merit.

410 The Defendant’s position is that the plaintiff has “manufactured, altered and tampered with evidence to deceive [the] Court by giving it the false impression that there is a seamless chain of custody of the [Samples]”. ²⁸¹ The defendant pointed to a number of DCLs where changes were made to the entries to assert that the plaintiff must have amended the DCLs after the fact to manufacture evidence for the suit. ²⁸² In my view, the contentions relating to tampering are wholly speculative and unsubstantiated.

411 As an example, the defendant took issue with the DCL of 4 May 2016. The first scientist who had filled in the DCL had written the date 4/4/16 in black ink, and then filled in the first four rows in black ink. The authorising signatory for his entries was entered in blue ink. Subsequently, Dr Cann filled in the next few rows in blue ink. Blue ink was also used to write over 4/4/16 such that the date read 4/5/16. It is unclear how the defendant manages to infer from the amendment of the date that there has been tampering of evidence. Either the authorising signatory or Dr Cann could have amended the date recorded by the first scientist, which was incorrect. It is not inconceivable that there will be human administrative errors in the filling up of the DCLs, which were completed by a miscellany of scientists on a daily basis as a routine matter, but to then suggest that these errors are indicative of the tampering of evidence is inappropriate.

412 Various discrepancies in the DCLs are pointed out by the defendant, which I do not discuss in detail. I am however satisfied that these discrepancies, which in any event only accounted for a small percentage of the total number of DCLs, may be explained by simple human error. For example, the 30 October 2015 DCL was not accurate as it reflected a same day check-out and check-in of Sample 2 although that was the same day where Sample 2 was returned to the Maidenhead Facility from external testing. But when presented with this alleged discrepancy, Ms Watts explained that she made an error when drafting her AEIC and proceeded to correct the discrepancy with the correct DCL (2 November 2015).

413 Another alleged discrepancy pertaining to the DCLs pertains to the colour code. In any given DCL, the colour code of the tin in which the diamonds are contained is required to be filled in. ²⁸³ Ms Watts explained that synthetic diamond samples will generally be allocated a green colour code. However, the defendant has highlighted various alleged inconsistencies in the colour code entries. For instance, the DCL of 18 March 2016 shows that Dr Cann checked out Sample 1 and Sample 2 in a red box. However, the DCL of 19 June 2017 and 21 June 2017 show that Sample 1 was checked out in a blue box. But Ms Watts’ evidence was only that synthetic diamonds would generally be allocated a green colour code. The defendant could have queried Dr Cann on why he had checked out the Samples in boxes of other colours, but chose not to. In the circumstances, I do not consider that the mere use of a different colour code suggests that there has been a break in the chain of custody for the Samples.

414 The plaintiff relies on certain screenshots taken of its internal drive as contemporaneous evidence to be examined alongside the DCLs in establishing the chain of custody of the Samples. While the defendant has pointed out alleged inconsistencies in relation to the timing of the screenshots, I am satisfied that the plaintiff has provided satisfactory explanations for these discrepancies. ²⁸⁴ For example, while the DCL of 21 July 2014 indicates that Sample 2 was checked out of the Strong Room on 8.30am for microscopy and checked in at 4.15pm, the screenshot of the internal drive suggests that the date and time of creation of the microscopy image was 5.48pm. While Ms Watts was unable to provide an explanation for this, Dr Cann explained that the timing reflected on the screenshots had to take into account the time zone of the computer through which the screenshots had been taken. ²⁸⁵ Dr Cann also stated that another explanation was that for tests which involved the processing of raw data, the time of creation of the image would reflect the time at which the data processing had been complete, which might be after the Samples were checked into the Strong Room. ²⁸⁶

415 For the reasons above, I reject the defendant’s contentions on the issues of provenance and chain of custody and find that on a balance of probabilities, the defendant is the responsible party for all three Samples.

416 On the issue of infringement, I find that the Samples infringe Claim 1 of SG 872, based on the Metripol measurements from experiments conducted at the University of Warwick. In addition, I also find, based on the EPR measurements which were also from experiments conducted at the University of Warwick, that Claim 62 of SG 872 must have been infringed as well. For SG 508, while the width of Claim 1 is such that there was technically infringement as Sample 3 was annealed resulting in a change of colour, my finding that SG 508 is not a valid patent is a complete defence to infringement.

417 The plaintiff’s case in relation to infringement is as follows: ²⁸⁷

(a) For Sample 2, the plaintiff has pleaded that it infringed Claims 1(ii), 1(iii), 16(ii), 35, 41-42, 49, 57-60, 62-70, 72, and 75-77 of SG 872;

(b) For Sample 3, the plaintiff has pleaded that it infringed Claims 1(ii), 1(iii), 16(ii), 19, 35, 41-43, 47-50, 52-53, 57-60, 62-72 and 75-78 of SG 872;

(c) For Sample 4, the plaintiff has pleaded that it infringed Claims 1(ii), 1(iii), 16(ii), 19, 35, 41-42, 49, 52, 57-60, 62-70, 72 and 75-77 of SG ‘872.

418 Before I turn to the Samples, I first deal with the defendant’s preliminary technical objections on the plaintiff’s use of its technical notes and its procedural omission.

419 The plaintiff relies on various technical notes to provide infringement (“the Technical Notes”):

(a) For Sample 2, the note titled “Characterisation of an optical grade single crystal synthetic diamond (NL 625-03) supplied by Microwave Enterprises” dated 5 October 2016, authored by Dr Martineau and Dr Cann (“Sample 2 Technical Note”);

(b) For Sample 3, the notes titled “Analysis of Pure Grown Diamonds Gemstones Gemstone NL 702” dated 5 October 2016, authored by Dr Martineau and Dr Cann (“Sample 3 Technical Note”) and “Summary of Evidence that NL702 had been Heat Treated (Annealed) after Growth” (“Sample 3 Heat Treatment Analysis”);

(c) For Sample 4, the note titled “Characterisation of an optical grade single crystal CVD synthetic diamond sample (NL719-06) supplied by IIa Technologies Pte Ltd” dated 5 October 2016, authored by Dr Martineau and Dr Cann (“Sample 4 Technical Note”).

420 The defendant contends that the Technical Notes are inadmissible hearsay evidence, as they are “mere summaries” of the results of various experiments conducted on the Samples. ²⁸⁸ The Technical Notes were not prepared by those who actually conducted the experiments.

421 The defendant’s argument that the Technical Notes are hearsay evidence is misplaced. They were prepared by Dr Martineau, working with Dr Cann, both of whom were responsible for and able to answer queries for the experiments. Insofar as some of the records were generated by others, it would not be practicable to call each witness who generated data from the measurements or the system. Such data and raw material would have been generated in the ordinary course of business and admissible under s 32(1)(b) of the EA. This exception also covers statements based on information supplied by other persons, which would in this case then include the University of Warwick and LZH.

422 The defendant also contends that Dr Newton and Dr Glazer’s expert opinion on the infringement of the product claims should be disregarded, as it was based on the Technical Notes which are inadmissible hearsay evidence. Further, neither of them were involved in or conducted any of the experiments. Given my finding that the Technical Notes are admissible, this contention falls away. Dr Newton and Dr Glazer were providing their expert opinion on the contents of these Technical Notes. Further, I should also point out that the defendant’s experts were also content to discuss the Technical Notes to justify their expert opinion of why the Samples were non-infringing. The defendant could have, on their behalf, sought a physical examination of the Samples, of the various machines used or of the tests conducted, or asked for repeat tests or experiments to be conducted on the Samples. ²⁸⁹ They preferred to rely instead on technical arguments.

423 The defendant contends that the plaintiff is not permitted to rely on experiments not contained in a Notice of Experiment, as compliance with O 87A r 6 of the Rules of Court (Cap 322, R 5, 2014 Rev Ed) (“Rules of Court”) is mandatory. Order 87A r 6 of the Rules of Court states as follows:

424 In Electrolux Northern Ltd v Black & Decker [1996] FSR 595 (“Electrolux”), Laddie J stated (at 610) that the consequences of a failure to comply with O 87A r 6 (under the English provision which is in pari materia) was as follows:

425 The defendant points out that the plaintiff has relied on the following experiments that were not part of its Notice of Experiment: ²⁹⁰

(a) Cross-polarised images;

(b) DiamondView images;

(c) Laue-X-ray Diffraction;

(d) FTIR Spectroscopy

(e) UV/Visible Absorption Spectroscopy measurement at 360nm and 515nm absorption bands and wavelengths;

(f) Photoluminescence at 488nm excitation.

426 In closing submissions, counsel for the plaintiff pointed out that items (b) and (e) were part of its Notice of Experiment, but accepted that (a), (c), (d) and (f) were not contained in the Notice of Experiment.

427 It is clear from Electrolux that notwithstanding the failure to comply with O 87A r 6 of the Rules of Court, the court still retains a residual discretion to allow such experiments into evidence. In my view, it is appropriate to allow the experiments into evidence, for the following reasons. The experiments here did not catch the defendant by surprise as they were found in the Technical Notes. Further, there was no prejudice to the defendant as while one intended rationale of a Notice of Experiment is to allow for the possibility of repeat experiments, it is clear that the defendant had no intention of asking for repeat experiments.

428 In this context, I add that the defendant’s decision not to ask for repeat experiments or to conduct its own experiments on the Samples is one that has legal consequences. First, save in exceptional circumstances, if the defendant chooses not to ask for a repeat of the notice of experiments, the court will accept that the steps described will produce the results alleged. As explained by Laddie J in Electrolux at 608:

429 Second, in determining the issue of infringement, the court places weight on actual experiments conducted, given that they are “inherently more transparent than a good deal of other evidence”. This was explained in Magnesium Elektron Limited v Neo Chemicals & Oxides (Europe) Limited [2017] EWHC 2957 at [77]–[79]:

430 It is with these two points in mind that I approach the Samples.

431 According to the Technical Notes, the Metripol measurements for Sample 2 are 0.407 (for mod sine delta max for 98% of the analysed area) and 5.39 x 10-5 (for delta n max for 98% of the analysed area). This falls within the SG872 Range. The Metripol, as discussed in the context of the validity of Claim 1 of SG 872, is used to obtain a quantitative measure of the birefringence of the diamond. The experiments themselves were conducted at the University of Warwick, which were then analysed in the Technical Notes. ²⁹¹

432 The defendant asserts that the Metripol results for Sample 2 did not prove that Sample 2 infringed Claims 1(ii) and/or 1(iii). This is because the Metripol system is incapable of proving that delta is less than π/2 and cannot accurately measure mod sine delta for a sample thicker than 0.25mm. ²⁹² I have rejected both these contentions above: see [194]–[218] above.

433 The Metripol measurements alone suffice to prove that Sample 2 had a low optical birefringence within the SG 872 Range.

434 For completeness, I deal with the defendant’s contentions on the cross-polarised images. The defendant asserts that the cross-polarised images of Sample 2 proves that it did not infringe Claim 1. All three images showed “significant areas of white”, when the only colour that ought to have been seen was black, according to the Michel-Levy chart. ²⁹³ In the course of the trial, a significant amount of time was also spent on a yellow streak found in one of the cross-polar images for Sample 2. However, Dr Kaminsky, the defendant’s own expert, testified that the white areas were due to over-exposure. ²⁹⁴ Dr Martineau gave evidence to the same effect. While Dr Kaminsky could not conclude what colour those areas would have been but for the exposure, and therefore concluded that the cross-polar images were unreliable, they could have revealed black areas as well. As for the yellow streak, the short answer to this is that for the purposes of the patent, the selected analysed area is defined at 1.3mm x 1.3mm of the Sample, and that is well away from where the yellow spot occurred. ²⁹⁵

435 According to the Technical Notes, the Metripol measurements for Sample 3 are 0.080 (for mod sine delta max for 98% of the analysed area) and 1.06 x 10-5 (for delta n max for 98% of the analysed area). This falls within the SG872 Range.

436 For Sample 3, the defendant refers to another cross-polarised image of Sample 3, not relied on up by Dr Newton, “which showed a significant increase in white colour across the face of the sample”. ²⁹⁶ The experts’ explanation of over-exposure applies equally here.

437 The defendant also asserts that Sample 3 was tampered with by the plaintiff. Specifically, Sample 3 was processed from a gemstone into a plate such that the optical birefringence of the original sample was materially altered. ²⁹⁷ However, Dr Nebel conceded that he did not expect the polishing of diamond to change the birefringence in the remaining material: ²⁹⁸

438  This is consistent with Dr Glazer’s opinion that polishing a diamond sample into a parallel plate would not affect the heterogeneity of the sample given the hardness of diamond material. ²⁹⁹

439 Page 32 of SG 872 itself specifies that in order to take birefringence measurements, “[s]amples are prepared as optical plates of known thickness”. In addition, Dr Kaminsky explained in his AEIC that it was “perfectly fine” to reshape a sample into a parallel polished plate”, stating as follows:

440 Dr Kaminsky’s objection was thus as to the perceived heterogeneity of strain and birefringence patterns in CVD diamonds, which I have rejected above: see [210] above.

441 There is also some contention between the parties as to whether Sample 3 was polished into a parallel-sided plate, or laser sawn. Dr Martineau’s evidence was that notwithstanding the Sample 3 Technical Note stating that the plate was laser sawn, further checks on the records had revealed that Sample 3 was polished. ³⁰⁰ This becomes relevant because Dr Nebel contended that Sample 3 could not be polished in a day. But the DCL for 24 November 2015 shows that Sample 3 was polished in a day. This is consistent with the laboratory notebook entry recording the progress of the polishing of Sample 3 in one day. ³⁰¹ It would be speculative to suggest that these contemporaneous documents were tampered with. Further, I also note that while Dr Nebel contended that Sample 3 could not be polished in a day, he had conceded that a diamond could be polished at up to 100 microns an hour, which contradicts his earlier evidence that it could be polished at 1 micron an hour. ³⁰²

442 According to the Technical Notes, the Metripol measurements for Sample 3 are 0.0231 (for mod sine delta max for 98% of the analysed area) and 3.22 x 10-5 (for delta n max for 98% of the analysed area). This falls within the SG872 Range. The defendant’s contentions here again can be addressed by the over-exposure of the images which I have discussed above.

443 I therefore conclude that Samples 2, 3 and 4 infringe Claim 1 of SG 872. In the light of this conclusion, it is unnecessary to deal with Mr Mehta’s rather circular arguments that the Samples could not have originated from the defendant, either because the defendant did not produce low birefringent diamonds or did not cut or polish diamonds. ³⁰³ Mr Mehta also gave evidence that the defendant stopped growing optical grade diamonds in February 2015, but this was contradicted by the contemporaneous documents. ³⁰⁴ It was, in my view, a lie concocted to distance the defendant from the Samples in the present case. Ms Lin Lin’s email dated 15 October 2015, addressed to Mr Pascal Pierra in respect of the Sample 4 transaction states: ³⁰⁵

Mr Mehta was therefore not a credible witness, and the veracity of the defendant’s alleged confidential process must be seen in that light, which I now turn to.

444 The plaintiff submits that the defendant has infringed Claim 62 of SG 872 on the basis of the test results on the Samples and Mr Mehta’s evidence given in the course of the trial. ³⁰⁶

445 The defendant disclosed two growth processes through Mr Mehta’s AEIC: the “High Purity Growth Process” and the “Standard Commercial Growth Process”. For the purposes of this suit, it is the Standard Commercial Growth Process that is relevant. This process, the defendant contends, comprised trade secrets that required to be limited to a confidentiality club. For convenience, I refer to this as the Confidential Process. The plaintiff does not accept that the Confidential Process accurately sets out the process used by the defendant to grow the Samples, and its CVD diamonds generally.

446 It is useful to begin with a chronology of the relevant events which led to the disclosure of the Confidential Process. ³⁰⁷

447 Initially, the defendant did not disclose any documents pertaining to its manufacturing process voluntarily in general discovery. This led to the plaintiff’s application for specific discovery in Summons No 1478 of 2018. That application resulted in a discovery order being granted on 27 August 2018 against the defendant to disclose various items, including its “method(s) of manufacturing the diamond material having product code no. 2PCVD50500N”. ³⁰⁸

448 On 28 September 2018, Mr Mehta filed an affidavit (the 30th affidavit), stating in the main that the defendant did not have and never had the documents it was ordered to produce. The plaintiff then filed Summons No 4960 of 2018 which sought, inter alia, an unless order for the defendant to comply with the discovery order.

449 On 30 November 2018, I rejected the plaintiff’s prayers for the defence and counterclaim to be struck out and for judgment to be entered against the defendant. In this regard, I digress from the issue of infringement to explain briefly why I rejected these prayers. The applicable principles in deciding whether to grant a striking out order was summarised in Grande Corp Pte Ltd v Cubix International Pte Ltd and others [2018] SGHC 13 at [76]:

450 In my view, the present case was not one in which such exceptional circumstances could be said to exist. More importantly, there were multiple issues which had to be canvassed at trial, and the issue of the defendant’s process was relevant only to infringement. If the patents were invalid, the defendant would in any event have a defence to infringement.

451 In the circumstances, I instead ordered for the defendant to explain in an affidavit its reasons for not having the relevant documents in its possession, custody or power. I highlighted that the non-compliance with the discovery order ought to be a matter dealt with in cross-examination at trial. Further, the failure to disclose might lead to an adverse inference being drawn against the defendant.

452 Against this backdrop, the defendant’s Confidential Process was finally revealed in Mr Mehta’s AEIC dated 1 February 2019. According to Mr Mehta, “[t]he formulas and descriptions of [the defendant’s] secret methods … [were] reproduced in written form for the first time. Prior to this, [the defendant] had never documented its secret processes”. ³⁰⁹

453 I disbelieve Mr Mehta’s statement that the defendant’s method of manufacturing CVD diamonds had not been documented before. The defendant’s own account was that these secret processes were the result of research and development for seven years between 2005 and 2012. It involved complex formulae and graphical representations. The defendant was a commercial entity with a turnover of US$90m. ³¹⁰ Yet, the defendant claimed that no documentation was necessary and that it had relied solely on Dr Misra and Mr Mehta’s memory to remember its Confidential Process and to key them into the scientific calculators and machines.

454 In my judgment, the defendant did not want to risk the possibility of the drawing of an adverse inference from the non-disclosure of its process. However, as will be evident from the points below, its process to grow the Samples infringed Claim 62 of SG 872. Under these circumstances, it designed a Confidential Process that [rest of sentence redacted]. This was contrived so as to avoid liability for infringement.

455 One key contention is the nitrogen concentration used by the defendant in its Confidential Process. In this regard, I place weight on the EPR measurements of the samples, which provide an objective indicator of the amount of nitrogen that has been present in the synthesis atmosphere when the Samples were grown. The EPR is a spectroscopic method employing magnetic fields and microwaves to study materials and molecules with unpaired electrons. In the present case, the EPR experiments were conducted by the University of Warwick and the measurements were then analysed in the Technical Notes. ³¹¹

456 According to the EPR measurements of the Samples, the concentrations of neutral single substitutional nitrogen within Samples 2, 3 and 4 are 118ppb, 460ppb and 130ppb respectively. ³¹² Referencing back to [220], these values are, as expected, below those prescribed by Claims 57 and 58, being 2.84 ppm and 1.136ppm respectively. Those product claims are therefore infringed as well. Dr Bergonzo explained that while there is no precise correspondence between nitrogen concentration in the solid phase and in the gas phase, the nitrogen concentration in the gas phase will always exceed the concentration of nitrogen incorporated in the diamond by a factor of 5 (ie, incorporation ratio of 0.2). As for Dr Nebel, he stated in his expert report that “[n]itrogen in diamond can be indicative of the used range of nitrogen in the gas atmosphere … The reported incorporation rates are spreading from 0.2 to 0.0001”. ³¹³ While the defendant points out that Dr Nebel was “referring to an incorporation ratio of nitrogen atoms to carbon atoms in the synthesis atmosphere into the grown diamond”, ³¹⁴ it is not clear how this can be read into Dr Nebel’s statement.

457 The plaintiff notes that by Dr Nebel’s own incorporation ratios, Samples 2, 3 and 4 must have been grown with at least 590ppb, 2ppm and 650ppb of nitrogen in the synthesis atmosphere respectively. The defendant’s response to this is to refer to a mismatched fraction, which I deal with at [459]–[459] below.

458 The EPR measurements alone therefore show that Samples have been grown with a process that had a nitrogen range of between 300ppb to 5ppm in the synthesis atmosphere. I note that in respect of the EPR measurements, Dr Nebel asserted that the results were unreliable because the experiments were not properly calibrated. For example, the reference sample that was used to calibrate the experiment for Sample 2 was only 0.44 carats whereas Sample was only 0.13 carats. ³¹⁵ Dr Newton’s response to this was that both the reference sample and Sample 2 are parallel-sided plates and their sizes were similar enough, such that the reference sample could be used with confidence. ³¹⁶

459 [[459] – [466] redacted]]

467 [[467] – [471] redacted]

472 The plaintiff’s case on infringement of Claim 1 of SG 508, based on the test results for Sample 3, is that collectively, the test results as stated in the technical notes on Sample 3 show that Sample 3 was annealed. ³¹⁷

(a) FTIR Spectroscopy was conducted on Sample 3 internally. The presence of certain absorption lines would be indicative of the presence or absence of certain point defects in CVD diamond. ³¹⁸ In the present case, the spectrum produced contained, inter alia, a weak line at 1341cm-1. This line was previously only observed for CVD synthetic diamond that had been exposed to heat treatment which has removed or reduced brown colour. Further, no absorption feature was observed at 3123cm-1, which is consistent with post-growth annealing at high temperature.

(b) Sample 3 was also internally tested using DiamondView and a photoluminescence spectrometer, which showed that Sample 3 was heat treated after growth. In particular, the combination of green fluorescence and blue phosphorescence for the DiamondView images is “often seen for nitrogen doped CVD synthetic diamond that has been heat treated (annealed) to improve its colour”. As for the photoluminescence spectra, which give an indication of the method used to produce the material and whether this involves high temperature treatment after growth, ³¹⁹ the detection of H3 defects (comprising two nitrogen atoms and a vacancy) suggested that Sample 3 had been annealed after growth. The presence of the N3 defect at 415.1nm and 427.7nm wavelengths also supported a finding that Sample 3 has been annealed as these lines are not seen in as-grown material.

473 The defendants contends that the plaintiff has not proven annealing to change the colour on various grounds. I reject these contentions for the following reasons:

(a) While the defendant claims that the Technical Notes are inadmissible, I have earlier explained, in the context of SG 872, that they are admissible pursuant to s 32(b)(iv) of the Evidence Act: see [420]–[422] above.

(b) The defendant points out that in SG 508 itself, it is stated that the observation of the 3107cm-1 line in CVD diamond is indicative that the material has been annealed according to SG 508. However, it is undisputed that no such line was observed. ³²⁰ In response, the plaintiff, relying on Dr Newton’s evidence, states that the presence of the 3107cm-1- line is only indicative that the diamond has been annealed. The absence of the line does not mean that the diamond has not been annealed, as it could be due to other factors such as the amount of hydrogen in the sample. ³²¹ I accept Dr Newton’s explanation on this point which was not contested by Dr De Weerdt.

(c) The defendant also contends that the plaintiff has not proved that Sample 3 was coloured before it was annealed. ³²² But the line at 1341 cm-1 is evidence that the diamond was originally of a brown colour: see [472(a)] above.

474 Nevertheless, whilst the Samples have been annealed, in view of my finding on validity, the defendant has a defence to infringement. This infringement of SG 508 could also point to infringement of WO 406, EP 482 or US 430 or Schmetzer, for that matter, given that I have found that these pieces of prior art would have taught the PSA that a CVD diamond could be annealed to change its colour

475 I add a note on the defendant’s described confidential process of annealing. [Remainder of [475] – [476] redacted]

477 Indeed the premise of the defendant’s case against the validity of SG 508 is that the annealing process is the same for all kinds of Type IIa diamond, quite regardless of their nitrogen content, and nitrogen structure and content differs across the three kinds of Type IIa diamond.

478 I therefore make the following orders:

(a) A declaration that SG 872 is valid and has been infringed;

(b) An injunction to restrain the defendant, whether by themselves, their directors, officers, servants, agents from (a) making, disposing of, offering to dispose of, using, importing and/or keeping products which infringe SG 872, and/or (b) using or offering for use in Singapore processes which infringe SG 872;

(c) An order for the delivery up and/or destruction, to be verified upon oath, of all products or articles which infringe SG 872;

(d) A declaration that SG 508 is invalid and has not been infringed; and

(e) An order for SG 508 to be revoked.

479 I shall hear counsel on costs. Regarding the prayer for an inquiry as to damages or an account of profits, this is to be dealt with in a second stage as provided for by Wei J’s order of court dated 31 March 2017 bifurcating the action to deal with validity and infringement issues first. The plaintiff may apply at the appropriate time.

480 I conclude with a note of appreciation to Prof Loh Kian Ping, who assisted the court as an assessor in this case.