Identification of Type IIa Blue CVD Synthetic Diamonds from Huzhou SinoC Semiconductor Co. in China.

Gemmological and spectroscopic characteristics are reported for two type IIa blue CVD synthetic diamonds from Huzhou SinoC Semiconductor Science and Technology Co. Ltd, China. These are the first relatively large (1.76 and 2.63 ct) blue CVD synthetics examined in NGTC’s laboratories, and their colour was slightly brighter than other blue synthetic diamonds that we have encountered. In the DiamondView, they fluoresced blue (with purple-red in one sample), which is unusual for CVD synthetics. The mid- and near-IR absorption spectra of one sample showed no hydrogen-related features, while the other synthetic diamond showed a weak absorption at 6853 cm⁻¹ attributed to hydrogen. The spectra of both samples had a very weak line at 1332 cm⁻¹ due to isolated nitrogen and a distinct band at 9282 cm^–1 related to radiation. A very strong GR1 absorption feature was detected by UV-Vis-NIR spectroscopy. Photoluminescence spectra obtained at liquid-nitrogen temperature recorded emissions related to radiation (mainly in the 480–510 nm region), N-V and [Si-V]^– centres, and several unassigned weak emissions. This combination of optical centres strongly suggests that these samples underwent post-growth treatment to improve their transparency before they were irradiated to produce blue colouration. [ABSTRACT FROM AUTHOR]