Feature Gems & Gemology, Fall 2007, Volume 43, No. 3

Natural Type Ia Diamond with Green-Yellow Color Due to Ni-Related Defects

Wuyi Wang, Matthew Hall, and Christopher M. Breeding

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Commonly seen in HPHT-grown synthetic diamonds with a green component, nickel-related defects were identified for the first time in a type Ia natural diamond with a strong green component. The 1.75 ct Fancy green-yellow diamond showed a strong peak at 1332 cm−1 in the IR absorption spectrum, strong absorption from the 1.40 eV center and the associated ~685 nm band in the Vis-NIR spectrum, and extremely strong emissions from Ni-related defects in the photoluminescence spectra—all of which proved that nickel was the primary cause of the green color.