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Identification of CVD-grown synthetic melee pink diamond
Hiroshi Kitawaki, Ahmadjan Abduriyim, Jun Kawano and Makoto Okano
Abstract: Forty-eight faceted intense orangey-pink 
CVD-grown
synthetic diamonds, most of which weighed less than 0.2 ct, have been examined in the GAAJ-ZENHOKYO laboratory. All proved to be coloured by the N-V centre that was formed by irradiation and annealing at low temperature after CVD synthesis and succeeding HPHT treatment. Using a combination of pinpoint inclusions and birefringence strain patterns, infrared absorption peaks in the range of 3150-2700 cm−1, significant photoluminescence absorption lines at 575, 637 and 737 nm, and DiamondViewTM and cathodo-luminescence images of layer growth patterns, CVD synthetic diamond can be distinguished from natural diamond. Annealing could change the colour of CVD diamond significantly from pink to purple but its colour was not stable and returned to its initial pink colour by UV radiation exposure in a short period. Features in the UV-Visible
absorption spectra will be affected by annealing and UV radiation reaction.
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