The New York laboratory of the Gemological Institute of America (GIA) recently certified the largest faceted blue synthetic diamond ever by the organization.
The emerald-cut, 5.03-carat, VS1 high-pressure, high-temperature (HPHT) type-Ⅱb stone was produced by New Diamond Technology (NDT), a company based in Russia, and one of the founding members of the International Grown Diamond Association. The stone was graded as fancy deep blue, a very attractive hue that contains no other colour component, a rarity among natural type Ⅱbdiamonds, according to the lab note.
NDT also produced the world’s largest known colourless lab-grown diamond, a 10.02-carat, E colour, VS1 stone cut from a 32.26-carat piece of synthetic rough and submitted to International Gemological Institute (IGI) Hong Kong last year.
Several distinctive features of this HPHT-grown blue diamonds were identified, including faint but sharp colour zoning and a cuboctahedral growth pattern. The examination also found two broad bands which have been reported previously in NDT’s type-Ⅱa and Ⅱb HPHT diamonds.
“As the size and quality of synthetic diamonds improve, careful identification is essential,” the note said. “Examination of this large Ⅱb synthetic diamond, combined with those previous reported from NDT, illustrates the rapid progress in HPHT growth technologies. This is a development that will eventually impact the jewellery industry.”
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