天然钻石与合成钻石的钻石观测仪鉴定特征研究
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摘要
通过钻石观测仪(Diamond ViewTM)结合紫外-可见-近红外吸收光谱(UV-Vis-NIR absorption spectra)、傅里叶变换红外光谱(FTIR)对天然钻石、经辐照与热处理的天然钻石、高温高压(HTHP)合成钻石与化学气相沉积(CVD)合成钻石进行了较系统的对比研究。结果表明:无色或近无色天然钻石的荧光颜色通常呈现较单一的蓝色,且无磷光,钻石荧光图像的内部较多可见呈闭合或非闭合的环状结构的生长线或不规则的折线。部分天然钻石无荧光且无磷光或者同时具有蓝色荧光与蓝绿色的磷光,但是鉴于CVD合成钻石较多同时具有荧光与磷光特征。因此,基于钻石有无磷光特征作为天然钻石与合成钻石的定性鉴别依据存在一定局限性。经辐照或热处理后的彩色天然钻石的荧光颜色主要呈非蓝色,部分样品因辐照处理使其自身的颜色发生改变的同时,并由此产生色心缺陷导致钻石荧光的颜色呈现多色性混杂特征。需进一步指出的是,基于UV-Vis-NIR吸收光谱特征与Diamond ViewTM图像中钻石的呈色特性是目前研究钻石经辐照处理较重要的鉴定方法。大部分CVD合成钻石的台面与亭部的局部位置出现独特的因CVD所致的清晰的平行层状生长条纹,同时具有淡蓝色磷光,该方法仍是目前相关CVD合成钻石判定的最为直接依据。
A systematic comparative study on the natural diamonds, the natural diamonds after annealing and irradiation and synthetic diamonds prepared by chemical vapor deposition(CVD) or high pressure and high temperature(HTHP) are investigated by Diamond View combined with UV-Vis-NIR absorption spectra and Fourier transform infrared spectra. The results show that the fluorescence′s color of colorless or near-colorless natural diamond shows a single blue color with no phosphorescence, closure or misclosure ring-structural growth lines or irregular lines are existed in theirs corresponding fluorescence images. Some natural diamonds have blue fluorescence and greenish blue phosphorescence. Meanwhile, parts of natural diamonds have the characteristic with no fluorescence and no phosphorescence, most of CVD synthetic diamonds have the characteristics of fluorescence and phosphorescence. Therefore, it is not scientific to identify of natural and synthetic diamonds based on theirs phosphorescence. The fluorescence′s color of natural diamond treated by irradiation and heat treatment display the other color expect blue. After irradiated, diamonds show large variations in their fluorescence patterns,particularly in the fluorescence′s color. Furthermore, the fluorescence color show mixed-color because of the color center defect resulted from irradiation. It should point out that the instruments of UV-Vis-NIR spectrometer and Diamond ViewTMare very powerful tool for studying irradiation in all sorts of diamonds until now. Unique fluorescence′s characteristics with parallel lamellar growth striations appear in the table and pavilion of the majority of CVD synthetic diamonds and are powerful evidences to identify CVD synthetic diamonds, which correlation with the preparative technique of chemical vapor deposition. Additionally, the Diamond ViewTMimages of CVD diamonds display light blue phosphorescent.
A systematic comparative study on the natural diamonds, the natural diamonds after annealing and irradiation and synthetic diamonds prepared by chemical vapor deposition(CVD) or high pressure and high temperature(HTHP) are investigated by Diamond View combined with UV-Vis-NIR absorption spectra and Fourier transform infrared spectra. The results show that the fluorescence′s color of colorless or near-colorless natural diamond shows a single blue color with no phosphorescence, closure or misclosure ring-structural growth lines or irregular lines are existed in theirs corresponding fluorescence images. Some natural diamonds have blue fluorescence and greenish blue phosphorescence. Meanwhile, parts of natural diamonds have the characteristic with no fluorescence and no phosphorescence, most of CVD synthetic diamonds have the characteristics of fluorescence and phosphorescence. Therefore, it is not scientific to identify of natural and synthetic diamonds based on theirs phosphorescence. The fluorescence′s color of natural diamond treated by irradiation and heat treatment display the other color expect blue. After irradiated, diamonds show large variations in their fluorescence patterns,particularly in the fluorescence′s color. Furthermore, the fluorescence color show mixed-color because of the color center defect resulted from irradiation. It should point out that the instruments of UV-Vis-NIR spectrometer and Diamond ViewTMare very powerful tool for studying irradiation in all sorts of diamonds until now. Unique fluorescence′s characteristics with parallel lamellar growth striations appear in the table and pavilion of the majority of CVD synthetic diamonds and are powerful evidences to identify CVD synthetic diamonds, which correlation with the preparative technique of chemical vapor deposition. Additionally, the Diamond ViewTMimages of CVD diamonds display light blue phosphorescent.
引文
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8 Thomas M M,Shane F M.Natural colorless Ia B diamond with Silicon-Vacancy defect center[J].Gems&Gemology,2014,50(4):293.
9 Welbourn C M,Cooper M,Spear P M.De Beers natural versus synthetic diamond verification instrments[J].Gems&Gemology,1996,32(3):156-169.
10 Sally E M.CVD synthetic diamond with unusual Diamond View image[J].Gems&Gemology,2014,50(1):67-68.
11 Altobelli M,Johnson P,Darley J.Diamond,artificially irradiated and coated brown[J].Gems&Gemology,2014,50(3):236-237.
12 Sun Yuan,Chen Hua,Qiu Zhili,et al..The Diamond ViewTMimages of natural diamonds from three commercial diamond localities in China and their significance[J].Acta petrologica Et Mineralogica,2012,31(2):261-270.孙媛,陈华,丘志力,等.中国3个商业性钻石产地天然钻石Diamond ViewTM图像及其意义[J].岩石矿物学杂志,2012,31(2):261-270.
13 Khan R U A,Martineau P M,Cann B L,et al..Color alterations in CVD synthetic diamond with heat and UV exposure:Implications for color grading and identification[J].Gems&Gemology,2010,46(1):18-26.
14 Wang Wuyi.Very large irradiated yellow[J].Gems&Gemology,2014,50(4):295
2 D′Haenens J U F S,Kyaw S M,Johnson P,et al..Near-colorless HPHT synthetic diamonds from AOTC group[J].Gems&Gemology,2014,50(1):30-45.
3 Wang W Y,Thomas M,Robert C,et al..Gem-quality synthetic diamonds grown by a chemical vapor deposition(CVD)method[J].Gems&Gemology,2003,39(4):268-283
4 Wang W Y,Ulrika F S D H J,Johnson P,et al..CVD synthetic diamonds from Gemesis Corp[J].Gems&Gemology,2012,48(2):80-97.
5 Song Zhonghua,Lan Yan,Shen Meidong,et al..Identification characteristics of undisclosed CVD synthetic diamonds found recently by NGTC[J].Journal of Gems and Gemmolagy,2012,14(4):30-34.宋中华,兰延,沈美冬,等.NGTC实验室发现未揭示的CVD合成钻石鉴定特征研究[J].宝石和宝石学杂志,2012,14(4):30-34.
6 Collins A T,Kanda H,Kitawaki H.Colour changes produced in natural brown by high-pressure high-temperature treatment[J].Diamond and Related Materials,2000,9(2):113-122.
7 Breeding C M,Wang W Y.Occurrence of the Si-V defect center in natural colorless gem diamonds[J].Diamond and Related Materials,2008,17(7-10):1335-1344
8 Thomas M M,Shane F M.Natural colorless Ia B diamond with Silicon-Vacancy defect center[J].Gems&Gemology,2014,50(4):293.
9 Welbourn C M,Cooper M,Spear P M.De Beers natural versus synthetic diamond verification instrments[J].Gems&Gemology,1996,32(3):156-169.
10 Sally E M.CVD synthetic diamond with unusual Diamond View image[J].Gems&Gemology,2014,50(1):67-68.
11 Altobelli M,Johnson P,Darley J.Diamond,artificially irradiated and coated brown[J].Gems&Gemology,2014,50(3):236-237.
12 Sun Yuan,Chen Hua,Qiu Zhili,et al..The Diamond ViewTMimages of natural diamonds from three commercial diamond localities in China and their significance[J].Acta petrologica Et Mineralogica,2012,31(2):261-270.孙媛,陈华,丘志力,等.中国3个商业性钻石产地天然钻石Diamond ViewTM图像及其意义[J].岩石矿物学杂志,2012,31(2):261-270.
13 Khan R U A,Martineau P M,Cann B L,et al..Color alterations in CVD synthetic diamond with heat and UV exposure:Implications for color grading and identification[J].Gems&Gemology,2010,46(1):18-26.
14 Wang Wuyi.Very large irradiated yellow[J].Gems&Gemology,2014,50(4):295