巴西金刚石的宝石矿物学特征

The gemological and mineralogical characteristics of Brazilian diamond

采用常规宝石学测试结合红外光谱、拉曼光谱以及Diamond View^(TM)测试,对巴西金刚石开展了常规宝石学、光谱学和荧光特征分析。结果显示,巴西金刚石表面微形貌特征丰富,可见多种形态的生长丘,三角、六边或不规则形态的溶蚀坑以及塑性变形滑移线等特征。巴西金刚石以ⅠaAB型为主(90%以上),N含量在400×10^(-6)~1 700×10^(-6)范围内,B心转化率介于15%~66%之间,具有高N含量和低-中等N聚集程度的特点。拉曼光谱分析进一步揭示了样品内部均残余压应力或者结晶度较差。Diamond View^(TM)发光图像显示ⅠaAB型金刚石样品具有蓝色和黄绿色调荧光;ⅠaB型金刚石样品为带有绿色调的蓝色和不均匀的蓝色荧光;Ⅱa型金刚石样品表现为暗橙色和蓝色荧光。

The Brazilian diamond samples were analyzed by conventional gemological testing instruments combined with Fourier transform infrared spectrometers(FTIR),laser Raman spectroscopy,and Diamond View^(TM).The results revealed that the surface microforms of Brazilian diamonds are extremely diverse,featuring various growth mounds,trigonal,hexagonal,or irregular fusion pits,as well as plastic deformation slip lines.The Brazilian diamond samples are predominantly composed of theⅠaAB type,accounting for over 90% of the total samples.It exhibits a nitrogen content ranging from 400×10^(-6)~1700×10^(-6)and a B core conversion rate between 15%and 66%.These findings indicate that Brazilian diamond samples are characterized by a high nitrogen content and a low to moderate degree of nitrogen aggregation.Raman spectroscopy analysis shows that there is residual compressive stress or poor crystallinity inside the sample.Diamond View^(TM)luminescence images reveal blue and yellow-green fluorescence is popular in BrazilianⅠaAB diamonds.TypeⅠaB diamonds exhibit blue fluorescence with green hues and an uneven blue fluorescence.The TypeⅡa diamond samples exhibit dark orange and blue fluorescence.