The Gemological Institute of America (GIA) recently studied a pink rough that resembled a natural stone, but it found to be a chemical vapor deposition (CVD) diamond.
The GIA received a 6.06-carat, pink specimen at its laboratory in New York. The stone appeared to be a natural octahedral diamond, with rounded faces and triangular etch marks typically found in such stones. However, it also displayed unusually sharp edges, according to an article in the fall issue of the institute’s quarterly journal, Gems & Gemology.
The initial spectroscopic analysis implied that the fancy-pink color was the result of multiple treatments, including High-Pressure, High-Temperature (HPHT). However, more testing revealed that the stone was a CVD lab-grown diamond, altered to look like natural, the GIA explained.
Infrared spectroscopy suggested the diamond was a type IIa stone, but its octahedral shape was unusual for a type IIa. Additional absorption features indicated it had undergone irradiation and annealing treatments. Meanwhile, DiamondView imaging further confirmed the diamond was CVD-grown and had been treated to produce its pink color.
Although the diamond displayed triangular etch marks typically associated with natural stones, further examination showed it was a treated lab-grown diamond. The findings highlight the importance of advanced testing methods, as a diamond’s surface appearance alone can be misleading when determining its origin.
This marks GIA’s first documented case of a CVD-grown diamond deliberately fashioned to resemble a natural octahedral crystal, although a near-colorless CVD specimen had previously been reported. The discovery spotlights increasingly sophisticated methods of imitating natural rough diamonds, the GIA added.
Image: The 6.06-carat CVD-grown pink rough. (GIA)
