Scientists find it ‘puzzling.’
This 0.26 ct pink synthetic diamond contains the first H4 defect GIA has observed in a CVD synthetic diamond. Photo by Robison McMurtry.
Diamond experts at the Gemological Institute of America aren’t sure what to think about a synthetic pink diamond they recently examined.
They found a defect, called H4, that is normally only seen in natural diamonds.
In fact, this was “the first observation of this defect in a CVD synthetic diamond,” according to a report by the GIA’s Troy Ardon, staff gemologist, and Christopher M. Breeding, senior research scientist and manager.
They note that diamond consists of a relatively simple lattice of carbon atoms wherein only a few impurities can substitute into the structure. The H4 defect consists of four nitrogen atoms and two vacancies.
This defect “is often seen in irradiated and annealed diamonds with suitable amounts of B-form nitrogen, and is a mature aggregate of nitrogen that is very difficult to achieve in synthetic diamond growth or even post-growth treatment,” they explain.
They’re not sure how such a defect could have occurred in the 0.26-carat round brilliant pink diamond submitted for grading at GIA’s Carlsbad laboratory. It was grown by chemical vapor deposition.
Ardon and Breeding say it’s possible the H4 was created during the irradiation and annealing process. But all in all, they find the presence of the defect “puzzling.”
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