The Gemological Institute of America (GIA) has discovered a synthetic layer that improved the weight and color of a natural diamond, and has warned that the phenomenon may be happening more often.
The cushion modified brilliant, 0.64-carat stone contained about 0.10 carats of chemical vapor deposition (CVD) diamond, the GIA estimated in a lab note last week. The lab-grown layer was greyish-blue, in contrast to the natural section’s yellowish color, giving the combined stone a fancy-greyish-greenish-blue appearance.
This was not the first time a stone of this type has turned up at the GIA: In 2017, it reported on a 0.33-carat, fancy-blue diamond that featured a CVD overgrowth similar to this one.
“With the second of these composites seen at GIA, this could be a new type of product entering the market,” research associate Troy Ardon and analytics technician Garrett McElhenny wrote in the note, which the GIA published in the Spring 2019 issue of its quarterly scientific journal, Gems & Gemology. “The resulting color was likely the main motivation for growing the CVD layer on top of the natural diamond, though the extra weight gained could also be a factor.”
