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Li J.,National Gold and Diamond Testing Center | Li J.,China Institute of Metrology | Weng X.,China University of Geosciences | Yu X.,China University of Geosciences | And 3 more authors.
Gems and Gemology | Year: 2013

The laboratory of the National Gold & Diamond Testing Center (NGDTC) encountered some plagioclase (moonstone) beads with blue adularescence. Fifteen of the 22 moonstones fluoresced moderate to strong bluish white to long-wave UV, with the fluorescence visible in fissures. Electron microprobe analysis of one bead and micro-infrared reflectance spectra of all 22 samples indicated a composition nearly identical to albite. The specimens with strong fluorescence exhibited 3053 and 3038 cm-1 peaks in their direct transmission infrared spectra, confirming impregnation by a material with benzene structure. This treatment can be detected with a standard gemological microscope by observing characteristics such as relief lines. © 2013 Gemological Institute of America. Source


Cheng Y.-F.,National Gold and Diamond Testing Center | Li J.-J.,National Gold and Diamond Testing Center | Zhu P.-M.,National Gold and Diamond Testing Center | Fan C.-L.,National Gold and Diamond Testing Center | Shan G.-Q.,National Gold and Diamond Testing Center
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2014

Taishan Jade is a kind of serpentine coming from western of Mount Taishan of Shandong province, which usually shows deep color. It can be deep developed and applied combining Taishan culture with coming from Mount Taishan and being named "Taishan jade". The key is to find out the main character that Taishan Jade different from Xiuyu jade of Liaoning and other serpentine in the habitat. The serpentines from Liaoning, Gansu jiuquan and xinjiang, which is alike to Taishan jade was tested respectively. The results show that the important characters are different from other habitats product: (1)color: The color of most taishan jade is dark of green; (2)character under the microscope: It often has reflect inclusion like Venus in shape, white inclusion like pillar, black mineral inclusion; (3)X fluorescence spectrum: There are metal elements, such as Fe, Ni, Cr and Mn etc. Its content is more obviously high than Xiuyu jade. Ni/Cr=2-4, while other habitats product is approached to 1.Laboratories which test Taishan jade should be equipped with reference sample. Source


Fan C.-L.,National Gold and Diamond Testing Center | Li J.-J.,National Gold and Diamond Testing Center | Cheng Y.-F.,National Gold and Diamond Testing Center | Wang Y.,National Gold and Diamond Testing Center | Zhu H.-W.,National Gold and Diamond Testing Center
Rengong Jingti Xuebao/Journal of Synthetic Crystals | Year: 2015

Using photoluminescence system, under the temperature of 297 K and 80 K, the application of argon ion laser (wavelength of 488 nm and 514 nm) of synthetic diamond, HPHT diamond, irradiation processing diamond and natural diamond was tested. The results show that the low temperature of 80 K test result is much better than normal temperature 297 K temperature, absorption peak produced by more defects may occur. Normally, for diamond sample 514 nm light excitation, can get more obvious peak, in 488 nm light source stimulated, can produce peak at 503 nm and 598 nm. CVD diamond synthesis, HPHT diamond, irradiation processing diamond samples at low temperature 80 K, 514nm excitation, there will be more obvious 575 nm, 637 nm peak, while natural diamond won't appear or only appeared weak and migration, both difference obvious, can be used as identification basis. Visible irradiation of natural diamond samples to 588 nm, 680 nm characteristic peak, and natural diamond, the CVD in the diamond synthetic diamond and HPHT processing does not appear the peak, can also be used as the basis for identification of irradiated natural diamond. ©, 2015, Rengong Jingti Xuebao/Journal of Synthetic Crystals. All right reserved. Source

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