Analytical Gemology and Jewelry (AG&J) head Dusan Simic launched a response to the decision of the GIA to grade laboratory-grown diamonds in what he calls a standardized fashion. “It is also unfortunate that the GIA only made its decision regarding LGDs after the recent publication of the third edition of Laboratory-Grown Diamonds - Information guide to HPHT and CVD-grown diamonds, by myself and Branko Deljanin,” Simic commented. “One of the main doubts and discussions that Branko and I had while writing the third edition of our book was precisely how LGDs would be graded in the future,” he said. “While Branko's commitment is to grade them like natural diamonds, which he does in his laboratory, I believe that grading should be different because natural diamonds and LGD are different products.”
“We waited for the GIA to decide and, unfortunately, they made a decision and published it when our book was already printed. This means that we were not able to comment on it in our book and to present facts in support of our two views. AGJ believes that the GIA’s decision is wrong. It is generally known that the color of CVD grown LGDs is unstable and changes even at relatively low temperatures in jewelry production or repolishing. Indeed, we discussed this very problem with participants at a globally attended webinar with CVD engineer Malay Hirani, co-author of LGD book on October15 during the launch of our new book.”
“Our new research also shows the presence of iron in the surface of polished LGDs. Undoubtedly, this is the due to polishing under increased diamond pressure on the polishing wheel. The structure of the unformed crystal, with many columns that are perpendicular to the table, allows iron doping as well as oil from polishing paste to be absorbed. For now, we do not know how iron will behave over time and how it will affect the color and clarity of the LGD,” Simic concluded.
Alex Shishlo for Rough&Polished
