A client of the Gemological Institute of America (GIA) wrongly submitted a natural diamond as a lab-grown stone, the organization said.
The GIA’s Carlsbad laboratory recently received the round brilliant, 2.23-carat, D-color diamond, which the customer had sent in for a synthetic-diamond grading report.
“When a declared synthetic diamond is submitted to a GIA laboratory, it is not often that the diamond turns out to be natural,” GIA analytics technician Garrett McElhenny and senior research scientist Sally Eaton-Magaña wrote in the Winter 2018 edition of Gems & Gemology, the institute’s quarterly scientific journal.
It was easy to mistake the stone for one created using High Pressure-High Temperature (HPHT). It had no clearly visible “strain” under detailed optical inspection — a pattern of lines that is usually absent in HPHT diamonds. The GIA only spotted the feature in a few scattered areas of the diamond following extensive efforts, it said.
Further tests confirmed it was from the earth, but also revealed additional pitfalls: The stone contained dark, natural inclusions that others might have mistaken for metallic flux, a common feature of HPHT diamonds, the institute explained.