The gemological and mineralogical characteristics of Brazilian diamond
The Brazilian diamond samples were analyzed by conventional gemological testing instruments combined with Fourier transform infrared spectrometers(FTIR),laser Raman spectroscopy,and Diamond ViewTM.The re-sults 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 dia-mond samples are predominantly composed of the ⅠaAB type,accounting for over 90％of the total samples.It ex-hibits a nitrogen content ranging from 400×10-6～1 700×10-6 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 ViewTM luminescence images reveal blue and yellow-green fluorescence is popular in Brazilian Ⅰ aAB diamonds.Type Ⅰ aB diamonds exhibit blue fluorescence with green hues and an uneven blue fluorescence.The Type Ⅱ a diamond samples exhibit dark orange and blue fluorescence.
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