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.