The Gemological Institute of America (GIA) has recently issued a lab report on the largest faceted blue laboratory-grown diamond studied so far. The report states that the GIA’s New York laboratory examined a 5.03 ct fancy-color HPHT-grown type IIb synthetic diamond this January. The stone was produced by Russian company NDT.

The lab said that stone reveals the rapid progress in HPHT growth technologies, a development that will eventually impact the jewellery industry.

The emerald-cut synthetic diamond was color graded as Fancy Deep blue. The report notes that faint but sharp color zoning was observed along with small metallic inclusions and a cavity at the girdle. These and other characteristics clearly indicated that the stone had been produced using HPHT.

Earlier, large colourless and near-colorless HPHT-grown diamonds by NDT have been investigated, with sizes up to 5.11 ct. The largest faceted colorless HPHT-grown synthetic diamond reported to date is a 10.02 ct E-color, VS1-clarity specimen, reported by IGI Hong Kong in 2015.

Now, this 5.03 ct sample becomes the largest HPHT-grown blue synthetic diamond examined at a GIA laboratory. As the size and quality of synthetic diamonds improve, careful identification is essential for the industry, the report concluded.