Identification Characteristic of HPHT-Treated Yellow Type Ib CVD Synthetic Diamond

Abstract

Synthetic type Ⅰb yellow diamonds are mainly grown by High Pressure High Temperature(HPHT) process, however, type Ⅰb CVD synthetic yellow diamonds have rarely been reported so far. A yellow type Ⅰb CVD syntheitc diamond sample was recognized for the first time in NGTC Shenzhen Laboratory during daily testing. It is critical for jewelry testing industries to summarize the identification characteristics of this yellow type Ⅰb CVD synthetic diamond, which will be helpful to identify problematic samples efficiently in the future. The means to identify the yellow type Ⅰb CVD synthetic diamond are summarized by collecting the infrared absorption spectrum, ultraviolet-visible absorption spectrum, ultraviolet fluorescence image and photoluminescence spectrum of the sample. The luminescence peaks at 737, 766 nm and 946 nm attributed to [Si-V] defects, and the parallel growth striations observied under fluorescence were diagnostic proofs of CVD synthetic diamonds. No doublet peaks at 596 nm and 597 nm were found and weaker 3 123 cm-1peak was detected, and the obvious 3 107 cm-1 peak, H3 (503.2 nm) emission and N3 (415.2 nm) emission suggested that it has undergone post-growth high temperature annealing to remove the as-grown brown coloration.