We visited the Chinese factory in early March 2016 and obtained 50 crystals (figure 1). The crystals were examined using the instrumentation and techniques applied to all diamonds submitted to GIA for grading; all exhibited the typical characteristics of HPHT growth and were identified as synthetic. These were basically colorless, with only a few metallic inclusions observed. These crystals showed typical cuboctahedral morphology, with well-developed (100), (110), and (111) growth sectors and a weakly developed (113) sector. The crystals we obtained ranged from about 0.5 to 1.2 ct each. Absorption spectra in the infrared region showed they were type IIa diamond, but trace absorption from boron was detected (2800 cm–1). Detailed gemological and spectroscopic analyses are ongoing and will be reported separately.
According to the manufacturer, large quantities of gem-quality colourless and blue diamonds are produced in this factory, in sizes up to 3.5 ct each. While the total production volume remains unclear, it is undoubtedly significant, and capacity is likely to expand in the near future. This strongly suggests that even more large HPHT synthetic diamonds will be introduced into the jewellery industry.
About the Authors: Wuyi Wang is GIA’s director of research and development. Thomas Moses is GIA’s executive vice president and chief laboratory and research officer.
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