A hpht synthetic diamond with special carbon isotope marking and a preparation method and an identity authentication method thereof

Abstract

The present application relates to the technical field of synthetic diamond, and particularly relates to HPHT synthetic diamond with special carbon isotope marking, and a preparation method and an identity authentication method thereof. 13 The present application adds graphite powder with specific 13 C / 12 C abundance into carbon source used in high-temperature high-pressure method for synthesizing diamond, controls the proportion of C in the whole carbon source, and converts the carbon source into diamond under high-temperature high-pressure conditions, so that the obtained HPHT synthetic diamond has preset carbon isotope composition. The carbon isotope composition, as an isotope mark built in the diamond crystal framework, can be corresponded to specific raw materials, specific batches, specific production processes or specific customer orders, so that the HPHT synthetic diamond is provided with a stable, tamper-proof, difficult-to-fake and easy-to-detect endogenous mark.

Description

Technical Field

[0001] This invention relates to the field of synthetic diamond technology, and in particular to an HPHT synthetic diamond with a special carbon isotope label, its preparation method, and its authentication method. Background Technology

[0002] Synthetic diamond, also known as lab-grown diamond, is primarily produced through high-temperature, high-pressure (HTHP) or chemical vapor deposition (CVD) methods. With the continuous maturation of synthetic diamond manufacturing technology, its applications in jewelry, industrial processing, electronic devices, quantum technology, biomedicine, and high-precision materials are becoming increasingly widespread. However, as the synthetic diamond market expands, issues such as product authenticity, traceability, and uniqueness identification are becoming increasingly prominent, posing significant challenges to the healthy development of the industry.

[0003] Firstly, in the emotional consumption market, especially in the emerging field of "life diamonds" or "commemorative diamonds," consumers have a high demand for the "uniqueness," "commemorative value," and "storytelling" of products. Existing life diamonds typically claim to be synthesized from carbon elements in human or pet hair, ashes, nails, skin tissue, or other carbon-containing biological samples, purified and used as a carrier for commemoration, inheritance, or emotional attachment. However, current technology generally cannot irrefutably prove, from a physicochemical perspective, that the final diamond actually originates from the specific carbon source specified by the consumer. In other words, consumers cannot confirm through conventional testing methods whether the diamond they purchase truly contains or primarily originates from the specified human or pet-derived carbon material.

[0004] The lack of such authenticity verification methods not only weakens the emotional value and market credibility of life diamond products, but also exposes related products to a crisis of trust, limiting the further enhancement of their commercial value and market premium. Therefore, the market urgently needs a unique identification technology that can be embedded in the diamond itself, directly linked to a specific source of raw materials, stable in existence, and easily detectable.

[0005] Secondly, in the entire synthetic diamond industry chain, product traceability, anti-counterfeiting, and batch identification capabilities have become key issues for industry development. For the high-end jewelry market, brands need reliable technical means to prove the product's origin, production batch, and brand ownership; for industrial-grade diamonds, producers and users need to be able to reliably identify diamonds from different batches, under different processing conditions, or with different performance grades; and for regulatory and testing institutions, a reliable technical system is needed to distinguish between natural diamonds, synthetic diamonds from different sources, and products from specific manufacturers.

[0006] Currently, common product identification and traceability methods mainly include laser marking, certificate numbering, packaging tracking, database registration, and detection of crystal morphology, impurity content, inclusion characteristics, and spectral features. However, all of these methods have certain limitations. External markings such as laser marking and certificates are easily counterfeited, altered, worn away, or separated from the physical object; while crystal form, color, nitrogen impurity content, boron impurity content, and other internal characteristics can reflect the growth conditions of diamond to some extent, these characteristics are usually greatly affected by fluctuations in the production process, are not necessarily unique, and are difficult to directly correspond to a specific source of raw materials.

[0007] Therefore, there is an urgent need in this field for a new technical solution that can implant a stable, detectable, difficult-to-counterfeit "endogenous identity card" directly related to the original carbon source into diamond during the synthesis stage. This identifier should be integrated with the carbon atom framework of diamond at the physicochemical level, without relying on external labels or additional markings, thereby achieving full-chain verifiable traceability from the source of raw materials to the final product. Summary of the Invention

[0008] The purpose of this invention is to address the aforementioned shortcomings of the prior art by proposing an HPHT synthetic diamond with a special carbon isotope label, its preparation method, and its authentication method.

[0009] The primary objective of this invention is to provide a method for preparing HPHT synthetic diamond with a specific carbon isotope labeling, comprising the following steps: S1 will be highly enriched 13 The nanoscale graphite powder of C is thoroughly mixed with ordinary micron-sized fine graphite powder to obtain mixed graphite powder; S2, the mixed graphite powder is used as a carbon source and assembled with a metal catalyst, diamond seed crystal, pressure transmission medium and heating components into a high-temperature and high-pressure synthesis block. The high-temperature and high-pressure synthesis block is then loaded into a high-temperature and high-pressure diamond synthesis device to synthesize diamond under high-temperature and high-pressure conditions. That is, the synthesis is carried out in the thermodynamically stable region of diamond, so that the carbon element in the mixed graphite powder is dissolved and diffused by the metal catalyst and crystallized on the surface of the diamond seed crystal to form diamond with a preset carbon isotope composition mark.

[0010] S3. After high-temperature and high-pressure synthesis, the synthesized product is cooled, depressurized, crushed, acid-washed, alkali-washed, or mechanically separated to remove residual graphite, metal catalyst, and other impurities, thereby obtaining HPHT synthetic diamond with a special carbon isotope composition label.

[0011] The ordinary micron-sized graphite powder can be natural graphite powder, artificial graphite powder, or graphite powder obtained by purifying and graphitizing biomass carbon sources, human carbon sources, pet carbon sources, or industrial carbon sources.

[0012] The ordinary micron-sized graphite powder preferably has a finer particle size to facilitate its high enrichment. 13 The graphite powder diluent C is thoroughly mixed. Further, the average particle size of the ordinary graphite powder is 35-40 μm, preferably around 38 μm.

[0013] Furthermore, in step S1, the mixing process employs one or more of the following methods: vibration mixing, ball milling mixing, planetary ball milling mixing, three-dimensional mixing, grinding mixing, and ultrasonic-assisted dispersion mixing, to achieve high enrichment. 13 C's graphite powder diluent is uniformly dispersed in ordinary graphite powder.

[0014] Furthermore, the mixed graphite powder can be used directly as a carbon source, or it can be used as a carbon source after being pressed, granulated, sintered, pre-pressed, or degassed. Preferably, the mixed graphite powder is pressed into tablets before assembling into a high-temperature, high-pressure synthesis block to increase the packing density of the carbon source in the synthesis cavity.

[0015] Furthermore, the high-temperature and high-pressure diamond synthesis equipment is a six-sided top press.

[0016] Furthermore, the high temperature and high pressure conditions include: a pressure of approximately 5 GPa, a temperature of 1300°C to 1500°C, and a holding time of 40 to 50 hours.

[0017] Furthermore, the metal catalyst is selected from one or more of iron, nickel, cobalt, manganese, chromium, titanium, and their alloys. Preferably, the metal catalyst is an Fe-Co alloy.

[0018] Furthermore, the diamond seed crystal can be a natural diamond seed crystal or a synthetic diamond seed crystal. The diamond seed crystal can be a single-crystal diamond seed crystal, a polycrystalline diamond seed crystal, or a diamond seed crystal with a specific crystal orientation. Preferably, the seed crystal has a {100} crystal facet.

[0019] The second objective of the invention is to provide an HPHT synthetic diamond with a special carbon isotope label prepared by the preparation method described above.

[0020] A third objective of the invention is to provide a method for identifying HPHT synthetic diamonds with special carbon isotope markings as described above, comprising the following methods: A1. The HPHT synthetic diamond sample with special carbon isotope labeling was etched with a laser beam to obtain carbon-containing aerosol. A2. The carbon-containing aerosol is introduced into a multi-receiver inductively coupled plasma mass spectrometer using a carrier gas for detection, and the measured values ​​are compared with those obtained using a diamond carbon isotope reference material. 13 C / 12The C ratio was corrected to obtain the δ¹⁴ C value of the HPHT synthetic diamond sample with special carbon isotope labeling. 13 C VPDB Value; its calculation formula is: ; in 13 C / 12 C sample The carbon isotope ratios obtained by the instrument from testing HPHT synthetic diamond samples are shown. 13 C / 12 C RM δ represents the carbon isotope ratio obtained by the instrument from testing the reference material. 13 C RM relative to VPDB The recommended values ​​for the reference material (RM) relative to the international standard reference material VPDB; A3. Using the above method, the HPHT synthetic diamond to be tested was analyzed to obtain its δ value. 13 C VPDB The value is used to confirm whether it is consistent with the above δ. 13 C VPDB The values ​​match to verify their identity.

[0021] Further, the δ obtained in step A2 13 C VPDB The values ​​are correlated with preset target values, raw material batch information, high-temperature and high-pressure synthesis batch information, customer information, or product certificate information to establish an HPHT synthetic diamond isotope labeling database; the δ values ​​obtained through subsequent step A3 are then analyzed. 13 C VPDB By comparing the value with the tag value recorded in the database, the identity of HPHT synthetic diamond products can be confirmed, batch identified, anti-counterfeiting verified, and raw material traceable.

[0022] Furthermore, the laser beam ablation site is located near the girdle, pavilion, or apex of the HPHT synthetic diamond sample, or at a location that does not significantly affect the appearance of the diamond.

[0023] Furthermore, the laser system can be a nanosecond laser or a femtosecond laser; the laser beam diameter can be 60 μm to 160 μm; the laser frequency can be 10 Hz to 250 Hz; the specific parameters are adjusted according to the signal strength and the size of the erosion pit.

[0024] Furthermore, during sample determination, the HPHT synthetic diamond sample with a special C isotope composition label and the diamond carbon isotope reference material are placed simultaneously in a laser ablation chamber and ablated and measured under the same or similar instrument conditions.

[0025] Furthermore, the carrier gas can be helium, argon, or a mixture of helium and argon. Preferably, helium is used to carry the aerosol generated by laser ablation out of the ablation pool, and then mixed with argon before being introduced into the plasma.

[0026] The reference interpolation method refers to measuring carbon isotope reference materials before and after the measurement of the unknown sample to correct for instrument quality discrimination, signal drift, and fractionation effects during the erosion process. The final carbon isotope composition is preferably expressed relative to the δ¹⁸O standard of the VPDB. 13 C VPDB The report is presented in value form.

[0027] In step S1, the high enrichment... 13 The amount of nanoscale graphite powder of C added is determined according to the following mass balance relationship:

[0028] Among them, R mix For the purpose of mixing graphite powder 13 C / 12 C ratio, n 13,common and n 12,common They are respectively ordinary graphite powder 13 C and 12 The amount of substance C, n 13,spike and n 12,spike Highly enriched 13 In C's graphite powder diluent 13 C and 12 The amount of substance of C.

[0029] Furthermore, it can be based on the target δ 13 C VPDB The target value is calculated by reverse deduction. 13 C / 12 C ratio, then calculate high enrichment 13 The quality of C graphite powder added.

[0030] Furthermore, the specific carbon isotope composition marker can be set to a single marker value, or it can be set to multiple marker values ​​of different levels or ranges. For example, different δ values ​​can be set for different HPHT synthesis batches. 13 C VPDB Marking ranges enables batch coding; specific δ values ​​can also be set for different customer orders. 13 C VPDB This value allows for personalized customization of the identifier.

[0031] Furthermore, to improve detection reliability, multiple erosion points can be selected on the same HPHT synthetic diamond sample for testing, and the average value of multiple test points can be used as the final isotope labeling value. For effective labeling, the fluctuation range of multiple test points must be within the analytical precision range.

[0032] Furthermore, the isotope markings of the present invention can be used in conjunction with laser waist codes, certificate numbers, spectral characteristics, nitrogen impurity content, boron impurity content, color, clarity, cut, crystal morphology, or other identification information to construct a multi-dimensional anti-counterfeiting and traceability system for HPHT synthetic diamonds.

[0033] Carbon is the only major element in diamond. Natural carbon is mainly composed of stable isotopes. 12 C and 13 Composed of C, where 13 C / 12 The carbon ratio can be determined using high-precision isotope analysis techniques. Once formed, the carbon isotope composition of diamond's crystal framework remains virtually unchanged under normal storage, wearing, processing, and testing conditions. Therefore, by controlling or adjusting the carbon source in the synthesis of diamond... 13 C / 12 The carbon ratio allows the resulting synthetic diamond to have a specific carbon isotopic composition, thus forming an isotopic fingerprint feature embedded in the diamond lattice. This feature does not rely on external encoding, is not easily damaged, and can be associated with a specific carbon source, a specific production batch, or a specific customer order, thus possessing excellent anti-counterfeiting and traceability potential.

[0034] Laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) is a high-precision analytical technique that allows for direct in-situ micro-area isotopic composition analysis of solid samples. This technique utilizes a laser beam to perform micro-ablation on the sample surface or a localized area, generating aerosol particles. These aerosols are then transported to an inductively coupled plasma (ICP) via a carrier gas for ionization. The isotopic ion signals are then simultaneously measured by a multi-collector mass spectrometry system, thereby obtaining the isotopic composition of the sample.

[0035] For diamonds, laser ablation eliminates the need for sample cutting and coating. The resulting micro-ablation pits are controllable in size, and the ablation area can be selected at the girdle, pavilion, or other locations that do not affect appearance or performance. Therefore, using LA-MC-ICP-MS to determine the carbon isotope composition of diamonds allows for rapid, accurate, and near-non-destructive testing of internal carbon isotope markings without significantly affecting the diamond's integrity or commercial properties. Based on this, a method was developed to prepare HPHT synthetic diamonds with special carbon isotope markings by controlling the isotope composition of the synthetic carbon source, and then characterizes these markings using LA-MC-ICP-MS. This method is of great significance for anti-counterfeiting, traceability, brand identification, batch management, and authenticity verification of synthetic diamonds.

[0036] This invention involves adding a specific [product / effect] to the carbon source used in the high-temperature, high-pressure synthesis of diamond. 13 C-rich graphite powder, used to regulate the overall synthesis of carbon sources. 13 C / 12 The carbon source is converted into diamond under high temperature and high pressure conditions, resulting in HPHT synthetic diamond with a predetermined carbon isotope composition. This carbon isotope composition serves as an isotopic identifier embedded in the diamond crystal framework, and can be associated with specific raw materials, specific batches, specific production processes, or specific customer orders. This provides HPHT synthetic diamond with a stable, tamper-proof, difficult-to-counterfeit, and easily detectable intrinsic marker.

[0037] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects: (1) The marking is embedded in the diamond crystal framework, which has high stability.

[0038] This invention modulates the carbon isotopic composition of the graphite carbon source used in HPHT diamond synthesis and controls the carbon source particle size to achieve high enrichment. 13 Nanoscale graphite powder of C is thoroughly mixed with ordinary micron-sized fine graphite powder to obtain a uniformly mixed graphite powder, which makes the carbon atom framework of the resulting diamond have a specific uniformity. 13 C / 12 The C ratio. This marking is not an external label attached to the surface of the diamond, nor is it informational for packaging or certificates; rather, it is an intrinsic physicochemical characteristic of the diamond crystal structure. Therefore, under normal wearing, processing, cleaning, transportation, and storage conditions, this marking is not easily lost, damaged, or tampered with.

[0039] (2) It is directly related to the carbon source for HPHT synthesis and is suitable for verifying the authenticity of raw materials.

[0040] This invention modulates the carbon isotope composition of the graphite carbon source before HPHT synthesis, ensuring that the isotopic characteristics of the resulting diamond directly correspond to the carbon source from which it was synthesized. For commemorative diamonds prepared from carbon materials derived from the human body, pets, or other specific sources, this invention can verify whether the diamond originated from a specified carbon source or a specified blending scheme by recording and detecting the carbon isotope composition.

[0041] (3) It is particularly well-suited for high-temperature and high-pressure synthesis processes.

[0042] The HPHT process typically requires the assembly of graphite carbon sources, metal catalysts, and seed crystals before synthesis. This invention utilizes this process characteristic, allowing assembly to be completed during the loading stage. 13 The quantitative mixing and homogenization of C-enriched graphite powder with ordinary graphite powder does not require complex modifications to high-temperature and high-pressure equipment, has strong process compatibility, and is easy to promote and apply on existing HPHT synthetic diamond production lines.

[0043] (4) It is difficult to counterfeit and has strong anti-counterfeiting capabilities.

[0044] Traditional laser markings, certificate numbers, or outer packaging labels are easily counterfeited, replaced, or tampered with. However, the carbon isotope markings of this invention are distributed within the diamond material and integrated with the diamond carbon framework. To counterfeit these markings, it is necessary to precisely control the carbon isotope composition of the carbon source during the HPHT synthesis stage and achieve the corresponding isotope uniformity and target values. This presents a high technical barrier and makes counterfeiting extremely difficult.

[0045] (5) The testing method is minimally or nearly non-destructive and does not significantly affect the product attributes.

[0046] This invention employs LA-MC-ICP-MS for in-situ micro-area carbon isotope analysis of HPHT synthetic diamond. The laser ablation area can be selected at locations such as the girdle that do not affect the diamond's appearance and performance. The ablation pits are small in size, having minimal impact on the overall integrity and commercial value of the diamond, and can be used for the detection and identification of finished diamonds.

[0047] (6) It can realize batch management, brand traceability and order-level coding.

[0048] By setting different δ values ​​for different high-temperature and high-pressure synthesis batches, different manufacturers, different brands, or different customer orders. 13 C VPDB The marked values ​​or marked ranges can be used to establish an isotopic coding system and database for HPHT synthetic diamonds. Subsequent testing of the diamond's carbon isotope composition is then sufficient for product origin identification, batch tracking, brand anti-counterfeiting, and quality management.

[0049] (7) The tag value can be designed, quantified, and database-based.

[0050] The carbon isotope labeling in this invention can be changed 13 The amount of C-enriched graphite powder added can be quantitatively controlled, and the resulting label can be expressed using δ¹⁴. 13 C VPDB The value is accurately represented. Therefore, this mark is not only unique and identifiable, but also facilitates standardized testing, database recording, and third-party certification. Attached Figure Description

[0051] Figure 1 This is a flowchart illustrating the preparation and characterization method of synthetic diamond with special carbon isotope composition marking based on the high temperature and high pressure method. Figure 2 yes 13 Carbon isotope analysis results of C-enriched HPHT diamond. RM is the diamond reference material. Figure 3 It has gradient δ 13 C VPDB Engraving results of coded HPHT diamond. Detailed Implementation

[0052] The following are specific embodiments of the present invention, which are described in conjunction with the accompanying drawings to further illustrate the technical solutions of the present invention. However, the present invention is not limited to these embodiments.

[0053] The raw materials used in Examples 1-2 below are from the following sources: High-purity C13 graphite powder (Sigma-Aldrich, 99 atom %) 13 C) Ordinary fine-grained graphite powder (Qingdao Jintao Graphite New Material Co., Ltd., 400 mesh) Example 1: Preparation of [product name] by HPHT method 13 C-enriched diamonds like Figure 1 As shown, weigh out 10.0 g of ordinary graphite powder, and separately weigh out... 13 Enrichment with C abundance of 99 atom% 13 2.5 mg of C graphite powder diluent was placed in an agate mortar for premixing, and then transferred to a vibratory mixer for 30 min to obtain mixed graphite powder with a preset carbon isotope composition.

[0054] The mixed graphite powder is pressed into graphite sheets, and then assembled with Fe-Ni alloy catalyst sheets, diamond seeds, magnesium oxide pressure transmission medium, graphite heating tubes, and insulating components into a high-temperature, high-pressure composite block. The composite block is then placed in a six-sided press and held at 5 GPa and 1400°C for 40 hours, allowing the carbon in the mixed graphite powder to dissolve and diffuse via a metal catalyst and crystallize and grow on the surface of the diamond seeds.

[0055] After synthesis, the temperature is lowered and the pressure is released. The synthesized product is then crushed and acid-washed to remove the metal catalyst and residual graphite, thus obtaining HPHT synthetic diamond with a special carbon isotope composition label.

[0056] The obtained diamond and a diamond carbon isotope reference material were simultaneously placed in an LA-MC-ICP-MS laser ablation cell. Under the same testing conditions, an intermittent testing sequence of reference material-sample-reference material was used for analysis to obtain the δ-value of the diamond. 13 C RM The value is [value missing]. This special diamond has a carbon isotopic composition of +21.43‰ compared to the diamond reference material, with an out-of-analytical precision of 0.88‰ (2SD) and good homogeneity. The test results are as follows... Figure 2 As shown, this aligns with the preset target, indicating that the carbon source for HPHT synthesis can be synthesized by controlling the parameters. 13 C / 12 The C ratio enables the effective implantation of specific carbon isotope labels into synthetic diamonds.

[0057] Example 2: Gradient δ 13 C VPDB Synthesis and characterization of encoded HPHT diamonds Three sets of mixed graphite powders were prepared respectively to achieve their target δ 13 C VPDB The values ​​fell into the first marked interval (D1), the second marked interval (D2), and the third marked interval (D3), respectively. All groups of mixed graphite powders were homogenized under the same vibrational mixing conditions and synthetic diamonds were prepared under the same HPHT synthesis conditions.

[0058] The carbon isotope composition of the three groups of diamonds was determined by LA-MC-ICP-MS. The results showed that ( Figure 3 ), the δ of three groups of diamonds 13 C VPDB The values ​​fall into their corresponding preset marked intervals, and there is significant distinguishability between different groups, where δ of D1 13 C VPDB =-16.92±0.12‰ (2s, n=3), δ of D2 13 C VPDB =-11.69±0.25‰ (2s, n=3), δ of D3 13 C VPDB =-0.08±0.06‰ (2s, n=3). The result is as follows. Figure 3 As shown, the results demonstrate that the present invention can achieve batch coding, source identification, and anti-counterfeiting traceability of HPHT-synthesized diamonds by controlling the carbon isotope composition of the high-temperature and high-pressure synthesized carbon source.

[0059] For any points not covered above, existing technologies shall apply.

[0060] Although specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, without departing from the direction of the invention or exceeding the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc., made to the above embodiments based on the technical essence of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing HPHT synthetic diamond with a special carbon isotope labeling, characterized in that, Includes the following steps: S1 will be highly enriched 13 The nanoscale graphite powder of C is thoroughly mixed with ordinary micron-sized fine graphite powder to obtain mixed graphite powder; S2, the mixed graphite powder is used as a carbon source and is assembled with a metal catalyst, diamond seed crystal, pressure transmission medium and heating components into a high temperature and high pressure synthesis block, and the high temperature and high pressure synthesis block is loaded into a high temperature and high pressure diamond synthesis equipment to synthesize diamond under high temperature and high pressure conditions. S3. After high-temperature and high-pressure synthesis, the synthesized product is cooled, depressurized, crushed, acid-washed, alkali-washed, or mechanically separated to remove residual graphite, metal catalyst, and other impurities, thereby obtaining HPHT synthetic diamond with a special carbon isotope composition label.

2. The preparation method according to claim 1, characterized in that, The average particle size of ordinary micron-sized fine graphite powder is 35-40 μm.

3. The preparation method according to claim 1, characterized in that, In step S1, the mixing is carried out by one or more of the following methods: vibration mixing, ball milling mixing, planetary ball milling mixing, three-dimensional mixing, grinding mixing, and ultrasonic-assisted dispersion mixing, in order to improve the uniformity of the isotopic composition of the carbon source.

4. The preparation method according to claim 1, characterized in that, Before assembling into a high-temperature and high-pressure synthesis block, the mixed graphite powder is subjected to tableting to increase the packing density of the carbon source in the synthesis cavity.

5. The preparation method according to claim 1, characterized in that, The high temperature and high pressure conditions include: a pressure of about 5 GPa, a temperature of 1300℃ to 1500℃, and a holding time of 40 to 50 hours.

6. The preparation method according to claim 1, characterized in that, The metal catalyst is selected from one or more of iron, nickel, cobalt, manganese, chromium, titanium and their alloys.

7. An HPHT synthetic diamond with a special carbon isotope label prepared by the preparation method according to any one of claims 1-6.

8. A method for identifying HPHT synthetic diamonds with special carbon isotope labeling as described in claim 7, characterized in that, Including the following methods: A1. The HPHT synthetic diamond sample with special carbon isotope labeling was etched with a laser beam to obtain carbon-containing aerosol. A2. The carbon-containing aerosol is introduced into a multi-receiver inductively coupled plasma mass spectrometer using a carrier gas for detection, and the measured values ​​are compared with those obtained using a diamond carbon isotope reference material. 13 C / 12 The C ratio was corrected to obtain the δ¹⁴ C value of the HPHT synthetic diamond sample with special carbon isotope labeling. 13 C VPDB Value; its calculation formula is: ； in 13 C / 12 C sample The carbon isotope ratios obtained by the instrument from testing HPHT synthetic diamond samples are shown. 13 C / 12 C RM δ represents the carbon isotope ratio obtained by the instrument from testing the reference material. 13 C RM relative to VPDB The recommended values ​​for the reference material (RM) relative to the international standard reference material VPDB; A3. Using the above method, the HPHT synthetic diamond to be tested was analyzed to obtain its δ value. 13 C VPDB The value is used to confirm whether it is consistent with the above δ. 13 C VPDB The values ​​match to verify their identity.

9. The identity verification method as described in claim 8, characterized in that, The δ obtained in step A2 13 C VPDB The values ​​are correlated with preset target values, raw material batch information, high-temperature and high-pressure synthesis batch information, customer information, or product certificate information to establish an HPHT synthetic diamond isotope labeling database; the δ values ​​obtained through subsequent step A3 are then analyzed. 13 C VPDB By comparing the value with the tag value recorded in the database, the identity of HPHT synthetic diamond products can be confirmed, batch identified, anti-counterfeiting verified, and raw material traceable.

10. The identity verification method as described in claim 8, characterized in that, The laser beam ablation site is located near the girdle, pavilion, or apex of the HPHT synthetic diamond sample, or at a location that does not significantly affect the appearance of the diamond.

Images