一颗由N、H相关缺陷共同致色的彩灰黄绿色钻石的鉴定特征OA

Natural green diamonds represent less than 0.07%of global natural diamond production and are consid-ered exceptionally rare gemstones.Previous studies have classified the coloration mechanisms of natural green dia-monds into four primary types:GR1,H3,H and Ni,with some specimens exhibiting combinations of these mecha-nisms.Among them,diamonds whose green color arises from H related defects constitute approximately 16%of all natural green diamonds;these are typically characterized by brownish or grayish hues,and those achieving the"Fancy"color grade are particularly scarce.In this study,a"Fancy"grayish yellowish green diamond was col-lected and subjected to comprehensive spectroscopic analyses,The results revealed the presence of an H related 615 nm absorption peak,along with 730 nm and 835 nm absorption bands that attenuate visible light in the red-orange spectral region.Additionally,nitrogen(N)related defects exhibited absorption peaks at 415 nm,452 nm,462 nm,and 478 nm,which absorb blue-violet light,resulting in a V shaped transmission window in the yellow-green region,this contributes significantly to the observed yellow-green appearance.A distinct 530 nm absorption band introduced a grayish component,ultimately yielding a grayish-green hue.Notably,no UV-Vis absorption fea-tures associated with GR1,H3 or Ni centers were detected.Based on existing classification criteria,this diamond would be categorized as having H related defects induced coloration.However,the author emphasizes that the contri-bution of N related defects to the overall color formation is substantial.Therefore,it is more accurate to attribute the color of this specimen to a synergistic effect between H and N related defects.