Abstract of Papers Presented at Annual Meeting of the Gemmological Society of Japan
2017 Annual Meeting
Displaying 1-22 of 22 articles from this issue
Abstract of Special Lecture at 2017 Annual Meeting of the Gemmological Society of Japan
Abstracts of Lectures at 2017 Annual Meeting of the Gemmological Society of Japan
  • Tomoko Fujiwara, Hidemaru Ogawa
    Pages 7
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    The production technology of the synthetic diamond is progressing rapidly today. Inspecting services separate TypeⅡ diamonds from TypeⅠ to which most of the natural diamonds belong, and then distinguish among the former type the natural stones from the synthetic ones by means of examining machinery and tools.

    This time we examined two round brilliant diamonds weighting 0.135ct and 0.140ct through FTIR, Vis-NIR, PL spectroscopy and Diamond-view imaging, and came to the conclusion that both of them are CVD synthetic diamonds. These stones showed the pink-to-blue color change after applying ultraviolet rays and 946nm (SiVO center) of Vis-NIR. We will do the comparative examinations with other examples of colorless to near-colorless CVD synthetic diamond.

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  • Hajime Uesugi, Hiroshi Saito, Tatsuya Odaki
    Pages 8
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    We took photoluminescence spectra of 50 typeⅡa natural pink and colorless diamonds, respectively. The measurements were carried out at liquate nitrogen temperature with 488nm and 515nm laser excitation. The FWHM of H3 in pink diamonds with 488nm laser excitation ranged widely from 0.35 to 0.96nm, as compared with the one in colorless diamonds from 0.25 to 0.63nm. 3 pink diamonds of them exhibited over 0.70, which had a remarkable 535.8nm peak with 515nm laser excitation.

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  • Hiroshi Kitawaki, Kentaro Emori, Mio Hisanaga, Masahiro Yamamoto, Mako ...
    Pages 9
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Identification of synthetic diamond requires advanced laboratory techniques such as FITR, photoluminescence (PL) analysis or DiamondViewTM analysis as well as standard gemological tests. In this report two kinds of synthetic diamond, which show features that make the stones appear as natural, are introduced. (1) a brown CVD synthetic diamond showing distinct linear color zoning under magnification and (2) a yellow HPHT synthetic diamond showing B2 center (platelet) and a C-H related peak in FTIR analysis. As these features only by themselves can be misidentified as those of natural diamonds, it is critical to identify a stone comprehensively by combining them with other analytical techniques.

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  • Masahiko HAYASHI, Hideo TAKAGI, Mana YASUI, Atsushi YAMAZAKI
    Pages 10
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    In 1962 synthetic diamond in Japan made by Toshiba Corporation. In 1960s, this synthetic diamond had collected as mineral specimen of Waseda University. The cathodoluminescence (CL) image of the synthetic diamond revealed a structure divided into small sectors showing blue and green colors.

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  • Kentaro Emori, Hiroshi Kitawaki
    Pages 11
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    We studied the application of discrimination analysis and logistic regression, which are kind of multivariate analysis, for the identification of synthetic and natural amethyst, synthetic and natural ruby and Paraiba-type tourmaline and found logistic regression shows better error rate than discriminant analysis for identification of natural and synthetic amethyst and natural and synthetic ruby.

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  • Hironori Kiyooka, Kazuyoshi Ogasawara
    Pages 12
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Quantitative evaluation of the agreement between the theoretical color and the experimental one is not easy. The color can be numerically represented by the chromaticity coordinates, which can be calculated from the absorption spectrum. In this work, chromaticity coordinates were calculated from the theoretical absorption spectra of emerald and the agreement between the theoretical color and the experimental one was evaluated quantitatively by calculating the color difference.

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  • Shota Takemura, Kazuyoshi Ogasawara
    Pages 13
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    A crystal of MgAl2O4 including impurity Co2+ is a gemstone known as blue spinel. The origin of the blue color is Co2+ ion which substitutes for Mg2+ in a 4-coordination site. Since the color and the absorption spectrum have close relation, it is important to analyze the optical absorption of the impurity ion. In this work, in order to reproduce and analyze the absorption spectrum of Co2+ in MgAl2O4 by first-principles calculation, we calculated the multiplet energies and the oscillator strength of the Co2+ ion by using the DVME method based on configuration interaction method.

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  • Chihiro Fukuda
    Pages 14
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Translucent and opaque gemstones are commonly waxing to improve luster, ex; jadeite and turquoise. LIBS can detect both of hydrogen and carbon. In this study, I try to detect the evidence of waxing using LIBS equipment. The results indicate that is useful method to detect waxing.

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  • Rika Iwamatsu, Tomoko Fujiwara, Rie Nanba
    Pages 15
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Recently, we identified some opals that show the same appearance but different refractive index and spectrum wavelength of infrared spectrum.

    These days, we receive many orders to identify opals neighboring chalcedonies and it is questioned to basic analyses such as refractive index.

    Beside basic analyses, we additionally tried the microscopic infrared spectroscope, the Raman spectroscope, and checking the Vickers hardness to reach the clear identification of opals and chalcedonies.

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  • Ayano Nakajima, Masaki Furuya
    Pages 16
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    There are a lot of gem deposit in YunNan province, China. Agates called ShiLinCaiYu and Huang Long Yu are highly evaluated in China. ShiLinCaiYu is a colourful agate. HuangLongYu is a yellow translucent chalcedony. Both are used for carving and their one of a kind characters are optimized.

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  • Shigenori OGIHARA
    Pages 17
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    In order to know the origin of Herkimer Diamond, powder X - ray diffraction was performed on the black substance (anthraxolite) coating the inside of the cavity. As a result, only reflection of graphite was observed. The black substance is graphite, not hydrocarbon. By Raman spectroscopy, it was found that the maximum temperature of graphite experienced was 200 degrees.

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  • Yusuke Katsurada, Ziyin Sun
    Pages 18
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Copper-bearing tourmaline, which shows vivid "neon blue" and blue to green colors, is now one of the most popular colored gemstone in the market place as known as "Paraíba tourmaline". Paraíba tourmaline has been considered to be an elbaite like most of other gem quality tourmalines since its discovery in late 1980s till liddicoatitic ones were reported in 2010 (Karampelas and Klemm, 2010). However, no other cuprian liddicoatites have been reported in detail.

    Thirteen samples examined in GIA's Tokyo laboratory were classified as Ca-rich and Li-rich liddicoatitic tourmaline by LA-ICP-MS. Comparing with cuprian elbaites from Brazil, Nigeria and Mozambique, these cuprian liddicoatites were revealed to have characteristic features of minor and trace elements. Geographic origins of these cuprian liddicoatites are not known at the moment.

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  • Makoto Tachibana
    Pages 19
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Flux-grown synthetic rubies and sapphires have been described in the gemological literature, but the techniques for growing the most beautiful crystals are kept secret. In this study, the flux method is used to grow ruby and sapphire single crystals. Ruby crystals showing the same habit with that of the legendary Ramaura ruby are successfully grown. Sapphire crystals and ruby crystals showing other habits are also grown.

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  • T. Katsumata, H. Mitomi, K. Miyajima, K. Takahashi, H. Fukushima, H. A ...
    Pages 20
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Mn doped spinel (MgxAl2O3+x) crystals have been grown by FZ technique with various starting compositions, x, from 0.3 to 1.7. Optical absorption and photoluminescence spectra from crystals grown under oxidized atmosphere are found to vary with composition. Crystals grown from Mg rich conditions are found to include MgO crystal based on X-ray powder diffraction patterns.

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  • Hyunmin Choi, Sunki Kim, Youngchool Kim
    Pages 21
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    A Korean company developed a new enhancement method of changing color of blue sapphire using an apparatus to produce synthetic diamond which is modified for mold press machine. They use the temperature of the treatment is to be in the range of not much higher than synthetic diamond product processing and applied low mechanical pressure.

    In this study, we conducted an experiment with pressure and temperature variable in order to analyze the gemological and spectroscopic properties of before and after enhanced sapphire. Changes of some inclusions and UV-Vis spectra observed after the enhancement are similar to these changes found in conventional heated corundum. However, a strong absorption band related to a structural OH group that did not exist in the infrared region of all samples was formed.

    Conclusive identification of these treated sapphires requires infrared spectroscopy and sometimes accompanied by some indication of standard heat treatment. Moreover, some fissures and fractures developed from their internal inclusions such as crystal and negative crystal. In addition, a definite color band and zoning usually became less prominent after enhanced by this method.

    For this study, also, we examined more than 20 sapphires, rough and polished. All of the samples were experimented with their general appearance, basic gemological properties, microscopic features, trace element chemistry, visible and infrared spectroscopy. We have described the properties of before and after new enhancement of blue sapphire in this study.

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  • K. Saruwatari, M. Suzuki, C. Zhou, P. Kessrapong, N. Sturman
    Pages 22
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    The DNA technique is a useful method to apply in the identification of pearl species, providing it is possible to extract DNA from the tiny quantities removed from solid pearl samples. Meyer et al. (2013)1 reported on a method used to identify the pearl oyster species Pinctada margaritifera, P. maxima, and P. radiata. In order to take this a step further, DNA methods were applied to P. fucata mollusks and their pearls in this study. On-site sampling was performed during Hamaage (harvesting) at Uwajima, Ehime prefecture, Japan, in January 2016. Twenty-eight pearl oysters used for culturing, the thirteen cultured pearls and two keshi pearls they contained, and nine donor oysters were collected. 16S rRNA extraction from mantle tissues was performed using a general phenol-chloroform extraction method, while 16S rDNA from the pearl samples were obtained using a similar destructive method to that described in Meyer et al. (2013)1. Both 16S rDNA genes extracted from mantle tissues of one donor shell and one pearl-culturing shell were fully matched with the complete sequence of P. fucata2. 16S rRNA genes extracted from the powder of four pearl samples were also found to match the sequence of P. fucata, though one recovered sequence was 350 bp. Thus the oyster and pearl samples from Uwajima, Ehime, Japan obtained in January 2016 were categorically identified as P. fucata species. From a methodology point of view, even after using the destructive method, it was possible to determine P. fucata 16S rRNA gene from only 5 to 10 mg of pearl powder sample weight compared to the previously reported quantities of pearl powder required (13 to 100 mg)1.

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  • Ikuo Atsumi
    Pages 23
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Shellfishes tend to contaminate an alien substance in the interior of the body by the same ingredient as a shell. That's caused by a mantle as the organ with which a shellfish makes its shell. A mantle sometimes makes a blister of the various forms with mother-of-pearl layer secretion in both natural and cultured oysters. Those are introduced in "The definition of a pearl and regulation about a nomenclature" (Association of gemological laboratories Japan) and "The pearl standard" (Japan pearl promotion society) etc., and classified as natural blister pearl work, a natural blister, cultured blister pearl work and a cultured blister. Those blister kinds were observed and the differences in the formative process was confirmed this time. This is a report of such observation of soft X-rays pictures and the section of samples.

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  • Junko Yazaki, Kentaro Emori, Hiroshi Komatsu
    Pages 24
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    We analyzed and classified the Golden South Sea Pears cultivated at some countries. There is the feature on the spectral properties of Golden South Sea Pearls, but its interference of pearls sometimes has an influence on its spectral properties. And there is the feature on analysis by LA-ICP-MS.

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  • Toru Yamamoto, Hiroshi Komatsu
    Pages 25
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Cultured akoya pearls using nuculeus mede of coral are distributed. After the pearl layers were formed on nucleus, it is difficult to distinguish coral from fresh-water shell. Therefore in the current study we searched about the method to prove that the pearl nucleus were made from coral.

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  • -The deterioration phenomenon of pearls which is caused by the denaturation of protain.
    Sayaka Nanjo, Junko Yazaki, Yasunori Matsuda, Hiroshi Komatsu
    Pages 26
    Published: 2017
    Released on J-STAGE: June 30, 2017
    CONFERENCE PROCEEDINGS FREE ACCESS

    Pearls have multilayer thin film structure which consists of calcium carbonate and a protein. The protain sheets play an important role in maintenance of the crystal layer. Pearls degrade with age by the wrong handling or state of preservation. We report the crack which are caused during processing among deterioration phenomena.

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