• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.5 no.5
• /
• pp.395-402
• /
• 2004

We need to develop technology of identifying high temperature high pressure(HTHP) synthetic diamond and HTHP treated natural diamonds from untreated natural diamonds to cope with sophisticated diamond enhancing technology. We had successfully identified synthetic diamonds using a vibrating sample magnetometer due to their ferromagnetic property. In addition, we identified the HTHP enhanced TypeIa, TypeIIa diamonds by employing non-destructive Fourier Transform Infrared(FTIR) spectroscopy.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.10 no.12
• /
• pp.3540-3545
• /
• 2009

Due to recent development of high temperature high pressure(HTHP) diamond synthetic and treatment technology, we need to identify the natural diamonds fast, reliable, and economically. We proposed using new method of UV fluorescence and X-ray Lang topography imaging for distinguishing one synthetic diamond from four natural colored diamonds. We observe unique local stress field uneven image in synthetic diamond using UV fluorescence and Lang topography characterization, while uniform images in natural diamonds. Especially, X-ray Lang method offered the better identification power with better high resolution on stress field images.

• Journal of the Mineralogical Society of Korea
• /
• v.21 no.4
• /
• pp.435-442
• /
• 2008

Natural, synthetic, and treated diamonds were studied by NMR and EPR. It was demonstrated that natural and synthetic diamonds, treated and non-treated diamonds, high pressure high temperature (HPHT) treated and electron beam treated diamonds could be distinguished among each other based on the $^{13}C$ NMR spectra acquired for relatively short periods of 100 minutes. The $^{13}C$ NMR linewidths of gem quality synthetic diamonds were broader than 1.6 ppm due to the paramagentic effects of transition metals, generally used as catalysts, while the linewidths of gem quality natural diamonds were narrower than 0.5 ppm regardless of the methods of treatment. The linewidth (0.5 ppm) for a HPHT treated, gem quality natural diamond was as broad as more than twice of the linewidth (0.2 ppm) of an electron beam treated diamond. The $^{13}C$ NMR signal intensities of treated, gem quality natural diamonds were as strong as more than 10 times of the intensities of non-treated, gem quality natural diamonds. When correlated with the concentrations of the paramagnetic defects (electrons) obtained from the EPR spectra, the relative $^{13}C$ NMR signal intensities increased in proportion to the concentrations of the paramagnetic electrons contained in each sample but the electron beam treated diamond was an exception. This suggested that the lattice component, in addition to the paramagnetic defect component, should also be considered in determining the $^{13}C$ NMR signal intensity of the electron beam treated diamond.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.27 no.4
• /
• pp.149-153
• /
• 2017

Recently, significant amounts of gem-quality colorless HPHT synthetic melee diamond have produced for the jewelry industry. Consequently, there have been reports of cases of fraud in the world diamond business. For example, intentionally selling synthetic diamond as natural diamond or intentionally mixing a natural diamond parcel with a synthetic. As a result, the separation of natural from synthetic melee diamonds has become increasingly critical. At present, 10,000 cubic hinge presses are used for the production of synthetic diamond in China. From among these, reportedly 1,000 presses are used for gem-quality diamond production. One press can produce up to 10ct melee-size diamonds in 24 hours. Randomly occurring pinpoint or flux-metal inclusions are diagnostic identification clues. However, some synthetic diamonds require advanced laboratory method for identification. In order to ensure consumer confidence, it is essential to screen melees so as to distinguish all synthetic goods.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.7 no.5
• /
• pp.817-822
• /
• 2006

Diamonds have been widely employed as polishing media for precise machining and noble substrates for microelectronics. The recent development of the split sphere press has led to the enhancement of low quality natural diamonds. Synthesized and treated diamonds are sometimes traded deceptively as high quality natural diamonds because it is hard to distinguish among these diamonds with conventional gemological characterization method. Therefore, we need to develop a new identification method that is cheap, fast, and non-destructive. We proposed using a new method of micro-Raman spectroscopy for checking the local HPHT residual stress to distinguish these diamonds from natural ones. We observe unique ~10f compressive and tensile strains at Type I and Type II diamonds after HPHT treatment. Our result implies that our proposed methods may be appropriate fur identification of the treated diamonds with appropriate reference samples.

• Journal of the Mineralogical Society of Korea
• /
• v.20 no.3
• /
• pp.175-180
• /
• 2007

FTIR technique was applied to delineate spectroscopic characteristics of natural, synthetic and irradiated diamonds. All of the samples studied in this work show the absorption peaks, which are generally observed in diamond as well as the specific one related to N in diamonds. Synthetic diamond is characterized with both the peaks of 1344 and $1128 cm^{-1}$ related to HPHT synthesis and specific $1050 cm^{-1}$ peak only observed in synthetic diamond, which can be used to discriminate natural from synthetic. Type (natural blue diamond: IIb, electron beam Irradiated blue diamond: Type Ia) can be used to discriminate natural from irradiated diamond. The intensity of specific $1450 cm^{-1}$ peak observed only in irradiated diamond is related with irradiation and annealing process.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.25 no.5
• /
• pp.188-192
• /
• 2015

Gemological and spectroscopic properties of HPHT synthetic diamonds from New Diamond Technology (NDT) company in St. Petersburg (Russia) were examined. Their color (colorless, near-colorless with some boron and Fancy blue with high boron content) and clarity ($VVS-SI_1$) grades were comparable to those of top natural diamonds. NDT synthetic diamonds fluoresced and phosphoresced blue or orange under SWUV light. Photoluminescence spectra revealed H3 center with very small intensity and NV centers. The intensity of H3 in NDT synthetic diamond has very weak in comparison with natural one. Using a combination of gemological and spectroscopic tests, gem-quality synthetic diamonds from NDT can be distinguished from natural diamonds of similar quality.

• Proceedings of the KAIS Fall Conference
• /
• 2009.12a
• /
• pp.1059-1062
• /
• 2009

폭발법에 의하여 얻어진 나노다이아몬드는 흑연상의 탄소를 일정 부분 갖으면서도 천연다이아몬드와 유사하게 높은 경도와 내마모 특성을 갖는 것으로 알려져 있으며, 흑연은 고온에 견디는 고체 윤활제로 사용되어 왔다. 따라서 나노다이아몬드를 오일과 물에 첨가하면서 용액의 점도 변화와 윤활 특성을 조사하였다. Fig. 2와 같이 3%(w/v)까지는 점도가 선형적으로 증가하는 것으로 나타났다.

• Journal of the Mineralogical Society of Korea
• /
• v.20 no.2 s.52
• /
• pp.97-102
• /
• 2007

NMR experiments with various pulse repetition delay time were carried out for the $^{15}N\;and\;^{13}C$ of a natural gem diamond and synthetic diamonds. The natural gem diamond had a weak $^{13}C$ peak at 34.1ppm when 30 second pulse repetition delay time was applied. Similar but more prominent $^{13}C$ peaks were observed at 34.2 ppm with 0.5 second pulse repetition delay time and at 34.7 ppm with 50 second pulse repetition delay time for the synthetic diamonds. Any meaningful $^{15}N$ peak was not observed for either natural or synthetic diamonds due to extremely low content of the $^{15}N$. Significant relationship was observed between relative spin-lattice relaxation times we estimated and the content of impurities. however, it was not possible to distinguish natural diamond from synthetic diamonds due to very similar characteristics of their $^{13}C$ NMR signals except relative spin-lattice relaxation times.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.14 no.3
• /
• pp.105-109
• /
• 2004

In this study, we analyzed the influences of appraising elements such as weight, color and clarity of natural diamonds on their value in the round brilliant cut diamonds. To analyze the influences of these elements on the value of diamonds, data were made from a Rapaport Diamond Report which is the most reliable source of diamond prices. As the result of this study, it is clearly understood that color and clarity equally influenced the value of diamonds as a whole, but there were some partial variations according to grades of both elements. That is, value of clarity was higher than that of color in higher-quality diamonds but value of clarity was lower than that of color in lower-quality diamonds. Also, value of diamonds were closely co-related by three main elements which were weight, color and clarity, but weight was the most influencing element on the value of natural diamonds.