中国3个商业性钻石产地天然钻石的Diamond ViewTM图像及其意义

对采自我国3个商业性产地山东蒙阴、辽宁瓦房店、湖南常德地区的236片/颗天然钻石样品进行了系统的DiamondViewTM(DV)荧光图像分析,结合CL照相和FTIR的定量计算,探讨了钻石样品DV图像发光结构模式和荧光颜色方面的差异性及其原因。结果表明,3个产地钻石的DV图像和CL图像显示的钻石生长结构基本一致;钻石的发光结构模式与钻石内部氮、氢元素的种类和浓度分布趋势没有明显的一致性,DV图像模式并不完全受钻石类型控制,但DV图像的色调与钻石存在的杂质元素及晶体缺陷有关。钻石的DV图像特征受钻石的生长环境、结晶条件、后期熔蚀、辐照损伤等因素综合制约。从统计学的角度看,3个产地钻石的DV发光模式和荧光颜色有一定的差异,这种差异可以作为区分不同产地来源的钻石的宏观的统计学特征。DiamondViewTM技术在揭示天然钻石生长结构方面和CL发光照相技术效果近似,但更加便利。

The Diamond ViewTM images of natural diamonds from three commercial diamond localities in China and their significance

The study of geographic locality of diamonds is the key to Kimberley Process Certification Scheme for Rough Diamonds.The UV fluorescence images provided by DiamondViewTM(DV) can be used to reveal the growth conditions of diamonds by analyzing their growth structures,therefore to provide evidence for diamond source.In this paper,236 natural diamonds from China’s three commercial producing localities of Mengyin,Shandong Province,Wafangdian,Liaoning Province, and Changde,Hunan Province were systematically investigated by DiamondViewTM.The DV images,together with their cathodoluminescence(CL) images and quantitative calculating results of Fourier-transform infrared(FTIR) spectra,were used to discuss the reason why diamonds from the three sources would differ from each other in their luminescence structure patterns and fluorescence colors.It is found that DV images of diamonds from the three sources basically coincide with the growth structures shown by their CL images,but without clear correlation between luminescence structure patterns of diamonds and the incorporation of nitrogen and hydrogen or concentration distribution patterns of these elements.Though DV images of diamonds are not fully decided by their types,the fluorescence colors do relate to some impurity elements and lattice defects in the diamonds.Generally speaking,DV images are influenced by various factors,such as crystallization conditions of diamonds,mantle fluid metasomatism,dissolution and irradiation damages.Statistics show that there are certain differences of DV image patterns and fluorescence colors between diamonds from the three localities, and the differences can be used as macroscopic statistical characteristics of possible different diamond localities.In addition,DiamondViewTM is similar to CL in photographic effects of revealing growth structures of natural diamonds and is more convenient in operation.