Spectroscopic characterization of yellow gem quality CVD diamond

CVD (chemical vapor deposition) diamond in the gem market today is dominated by colorless and pink material. However yellow CVD material is also found and it is concluded that all the yellow CVD diamonds found in the gem market have been post growth HPHT (high pressure high temperature) processed. This study shows that HPHT and LPHT (low pressure high temperature) treatments are essential for removal of the brown and gray color associated with as grown CVD material. The distinguishing temperatures and conditions of these treatments can be determined from the spectroscopic study of vacancy-related optical centers. [Display omitted] •Gem quality CVD diamonds of intense yellow color are nitrogen doped and in most cases HPHT-treated.•HPHT-treated nitrogen-doped CVD diamonds show higher efficiency of formation of NVN defects detected as H3 and H2 centers as compared with LPHT-treated ones.•The dominating optical centers in photoluminescence of yellow CVD diamonds are the 462 nm and 498 nm centers excited with 325 nm laser, the 503.2 nm (H3) center excited with 457 nm laser and the 850 nm and 986.2 nm (H2) centers excited with 830 nm laser.