Editor’s Note
**Editor’s Note:** In this Saturday Long Read, GIA legend Tom Moses reflects on his nearly 50-year career and shares candid regrets about the industry’s—and his alma mater’s—approach to lab-grown diamonds. This frank conversation, supported by GN Diamond, offers a rare, unvarnished perspective from a retiring insider.
In today’s Saturday Long Read, the GIA legend discusses what he thinks the industry, and his alma mater GIA, got wrong about lab-grown diamonds. Ad support from GN Diamond.
Jul 11, 2026
GN Diamond
Tom Moses exit interview, take two
After Tom Moses announced he was leaving GIA after nearly 50 years with the organization, he and I did an exit interview for JCK. But we also discussed having a franker talk after he had left GIA (which, as it so happens, was after I left JCK).
Here, GIA’s former chief research and laboratory officer—who is still mulling over what he wants to do next—shares his unvarnished opinion about GIA’s (since reversed) decision to issue Four C’s grading reports, his thoughts on lab-grown and grading terminology, and his excitement over GIA’s pending fancy cut grades.
Moses: I would say there’s two or three things that in hindsight could have been done better, industry-wide and perhaps at GIA. I think the nomenclature has become confused. I remember working 30, 40 years ago on nomenclature, with the FTC and other trade organizations. The terms that were in place for a long time were “synthetic,” “laboratory-grown,” “laboratory-created,” and “[maker]-created.” I always used them interchangeably.
But the industry has become sloppy in its use of nomenclature, which has resulted in looser usage. All of a sudden, both natural and laboratory-grown diamonds were being described as the same thing. I think that made the situation more challenging and, in a way, misleading.
There’s a saying: “How do you know where you’re going if you don’t know where you’ve been?” I think that applies to synthetic gem material. A French chemist, Auguste Verneuil, first used the term “synthetic” with the introduction of synthetic rubies. When they came to the market, it was a shock. Synthetic rubies got mixed in with fine rubies until there were ways to distinguish them.
We should have done a better job in telling the story of the path of other synthetic gem materials to the retailer and the consumer.
Then the technology improved, and the prices became less and less. Synthetic emeralds followed the same path. Tom Chatham’s father [Carroll] originally produced them, as I recall, at about $400 a carat. And then Russian chemists and others produced synthetic emerald for a much lower cost, and the price dropped.
Instead, the debate about laboratory-grown and natural diamond has become a stone-throwing thing, and that doesn’t help anyone.
The worrisome point is that, just a year ago, the price of laboratory-growns was two or three times what it is now. Yet, some of these large margins still exist. I worry about the impact on the industry with consumers paying more than they should.
When you mention sloppiness about nomenclature, what exactly do you mean?
Moses: Calling something a diamond without prefacing it with “man-made,” “[maker]-created,” or “laboratory-grown.” That violates the FTC Guidelines. People saying that laboratory-grown and natural are the same. If they were the same, we wouldn’t be able to distinguish them. I worry about the collateral longer-term impact this behavior will have.
Diamonds and man-made diamonds are different products and should be represented accurately. Synthetic or man-made gems have, for the most part, followed the same path: disruption at introduction, the development of diagnostic methods to separate them from their natural counterparts, significant reduction in production costs, and overall acceptance and success in the marketplace. Clearly, laboratory-grown diamonds are following that trend.
Moses: That was something we thought a lot about. We had two ideas: coming up with a different nomenclature and using a hybrid system. In hindsight, I believe we should have used a different nomenclature. The Four C’s were created on a continuum of rarity. Most CVD as-grown production is light brown, and then it’s decolorized at high temperature and pressure. If I treat a diamond more efficiently, it shouldn’t rank higher on a rarity scale.
We could have said “top white” and “second white” and that also would have been clear.
GIA used to issue Four C’s grading on its lab-grown reports. Courtesy: GIA
Why was that decision made? I remember it was done during COVID, when everyone’s business was down.
Moses: COVID and its influence on business was part of the decision. There were also requests from the industry for those reports. In retrospect, I don’t believe that was the best decision to make. It had the unintended consequence of misleading consumers.
Moses: This system will be a benefit for the entire pipeline. Manufacturers will have more options to decide what shape to cut and still receive a top cut grade. This will result in greater yield in many cases, and a better utilization of the raw materials.
Tom Moses can be reached at [email protected].
