ColumnistsJul 07, 2026
Peter Smith: Diamond Branding and the Origin ParadoxA podcast prompted Smith to share his views on where origin fits into the natural diamond story and the viability of branded diamonds.
EditorsOct 20, 2016
Why the GIA Grades Lab-Grown Diamonds Like It Does
The GIA’s Tom Moses explains the reasoning behind the more general color and clarity grades the lab assigns to synthetic stones.
The 5.19-carat diamond on the left and the 10.08-carat blue diamond on the right are both lab-grown stones recently examined by the Gemological Institute of America’s laboratory in Hong Kong. (Photo credit: left picture, Terry Leung and Johnny Leung; right picture, Johnny Leung, both courtesy of GIA)
Earlier this week, I wrote a story about two large lab-grown diamonds--one 5.19 carats and the other a 10.08-carat blue--recently examined by the Gemological Institute of America’s laboratory in Hong Kong.
In both articles, I noticed the GIA using the following terminology to refer to the stones’ color and clarity: “J-equivalent color” and “VS2-equivalent clarity” for the white diamond, and color equivalent to “fancy deep blue” for the colored stone.
This terminology, for me at least, raised questions about the GIA’s approach to grading synthetic diamonds.
On Wednesday, the very knowledgeable Tom Moses, the GIA’s executive vice president and chief laboratory and research officer, took some time to explain it to me.
Moses said the GIA has been issuing Synthetic Diamond Grading Reports for about 10 years.
On these reports, the GIA does not give specific color or clarity grades.
Instead, Moses said, it grades lab-grown diamonds in broader terms, calling, for example, stones in the D-E-F range “colorless” and those in the G-H-I range “near colorless.”
For clarity, the lab uses only VVS, VS, SI or I for synthetic diamonds.
Why?
Because, “by their very nature, when they grow these diamonds, they are traditionally nitrogen poor,” Moses said, which is, incidentally, also what makes them Type IIa. In addition, many, though not all, CVD-grown diamonds come out a sort of brown color and then are de-colorized through a treatment process to make them colorless or near colorless.
All this is to say that these stones are not going to have the same range of color (D to Z) as mined diamonds, which is why the GIA chooses to use broader categories in grading them. They are grown to be as clear as possible, too, which is why the GIA also uses broader terms for clarity.
The GIA’s grading system, which was created long before the proliferation of lab-grown stones that we see today, was “developed for normal mine run, which doesn’t change. That’s nature,” Moses noted.
However, when the GIA publishes research articles online--like this one on the 5.19-carat diamond that appeared earlier this month--it uses terms such as “J-equivalent color” and “VS-equivalent clarity” to give readers a clearer picture of the stone.
Moses said despite what some people seem to think, the GIA is not doing this to “punish diamond growers.” Rather, the lab just sees it as the most logical way to describe lab-grown diamonds.
In both articles, I noticed the GIA using the following terminology to refer to the stones’ color and clarity: “J-equivalent color” and “VS2-equivalent clarity” for the white diamond, and color equivalent to “fancy deep blue” for the colored stone.
This terminology, for me at least, raised questions about the GIA’s approach to grading synthetic diamonds.
On Wednesday, the very knowledgeable Tom Moses, the GIA’s executive vice president and chief laboratory and research officer, took some time to explain it to me.
Moses said the GIA has been issuing Synthetic Diamond Grading Reports for about 10 years.
On these reports, the GIA does not give specific color or clarity grades.
Instead, Moses said, it grades lab-grown diamonds in broader terms, calling, for example, stones in the D-E-F range “colorless” and those in the G-H-I range “near colorless.”
For clarity, the lab uses only VVS, VS, SI or I for synthetic diamonds.
Why?
Because, “by their very nature, when they grow these diamonds, they are traditionally nitrogen poor,” Moses said, which is, incidentally, also what makes them Type IIa. In addition, many, though not all, CVD-grown diamonds come out a sort of brown color and then are de-colorized through a treatment process to make them colorless or near colorless.
All this is to say that these stones are not going to have the same range of color (D to Z) as mined diamonds, which is why the GIA chooses to use broader categories in grading them. They are grown to be as clear as possible, too, which is why the GIA also uses broader terms for clarity.
The GIA’s grading system, which was created long before the proliferation of lab-grown stones that we see today, was “developed for normal mine run, which doesn’t change. That’s nature,” Moses noted.
However, when the GIA publishes research articles online--like this one on the 5.19-carat diamond that appeared earlier this month--it uses terms such as “J-equivalent color” and “VS-equivalent clarity” to give readers a clearer picture of the stone.
Moses said despite what some people seem to think, the GIA is not doing this to “punish diamond growers.” Rather, the lab just sees it as the most logical way to describe lab-grown diamonds.
He added that from a consumer perspective, he doesn’t think there is that much demand for specific color grades for lab-grown diamonds. Rather, they’re just happy to have a ring or a pair of earrings that are real diamonds but for a lower price.
“They’re going to say, ‘It looks nice. They sparkle. They’re the price I want to spend. I’ll take them.’”
(I think this same argument could be made for mined diamonds as well, but that’s another topic for another time.)
Moses said while lab-grown diamond companies do ask the GIA to do it differently, he doesn’t see the GIA altering its system in the near future, especially with the improving diamond-growing technology producing more stones of high color and clarity.
“Our mission is to serve the consumer and provide clear and accurate information,” he said. “Although we listen to the industry, ultimately, we are here to serve the public.”
“Right now, I just don’t see a reason why we would make that change.”
More on Editors
The Latest
Events & AwardsJul 07, 2026
JA Announces 2026 Impact Initiative RecipientsThe association selected eight recipients for the funding program, which is in its second year.
TrendsJul 07, 2026
Amanda’s Style File: Ruby, White and Blue Whether celebrating America’s 250th birthday or the USA’s World Cup run, July birthstone jewelry can double as a patriotic accessory.
Brought to you by
Wedding Band Trends 2026: Personalization Takes Center StageColored gemstones, artisan finishes, mixed metals, and meaningful details are shaping demand in bridal jewelry.
CrimeJul 07, 2026
Thieves Steal Millions in Jewels From France’s Musée LaliqueAround 20 pieces of jewelry were stolen from the museum dedicated to French jeweler and glassmaker René Lalique.
Weekly QuizJul 01, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
CollectionsJul 07, 2026
Robinson Pelham Is Partying Like It’s 1996The “Summer of ’96” campaign and collection celebrate the year the brand was founded for its 30th anniversary.
SourcingJul 06, 2026
Gemfields CEO Sean Gilbertson Steps DownAfter eight years, Gilbertson is leaving his post at the mining company, which is currently facing a slew of operational challenges.
Brought to you by
Building the Future of Jewelry Retail: DCA Expands Education, Leadership Development, and Workforce SolutionsDCA is preparing the next generation of professionals by supporting workforce development, leadership growth, and career advancement.
IndependentsJul 06, 2026
Bachendorf’s To Open Fifth Store In DallasThe new location is set to open this winter, featuring the retailer’s first rotating jewelry designer residency.
MajorsJul 06, 2026
Graff Names BTS Star Jung Kook as New AmbassadorThe pop artist appears in the latest campaign for the “Laurence Graff Signature” collection.
CollectionsJul 06, 2026
Pandora’s New Baroque Pearl Collection Is a Whimsical ‘Wonder’One-of-a-kind pearls take the shape of ice cream cones, frogs, submarines, and other imaginative charms.
SourcingJul 02, 2026
London Diamond Bourse Elects First Female PresidentCharlotte Rose said her election is “a sign that this is an industry capable of change.”
Supplier BulletinJul 02, 2026
Elevating Retail Showcases with Today's Necklace & Bracelet TrendsSponsored by Rio Grande Jewelry Supply
TrendsJul 02, 2026
Oscar Heyman’s Flag Brooch Celebrates AmericaThe American jewelry house, founded by Latvian immigrants, has been creating American flag brooches since 1917.
IndependentsJul 02, 2026
D. Geller & Son Partners with KSU Art Students on Store MuralThe artwork celebrates the Atlanta jeweler’s legacy and symbolizes its commitment to supporting local artists and its community.
Events & AwardsJul 02, 2026
Stratus Estate Buyers Offers Jewelers Turnkey Buying EventsIts team can evaluate jewelry and watches, as well as luxury handbags, artwork, and collectibles.
SurveysJul 01, 2026
Consumer Confidence Ticks Up in JuneFalling oil prices were a factor in the slight month-over-month improvement.
CollectionsJul 01, 2026
Rio Grande Launches First Finished Bridal CollectionThe new offering comprises more than 120 bridal and engagement ring styles with natural and lab-grown diamonds.
WatchesJul 01, 2026
Rolex Unveils Clock at Rockefeller CenterThe clock is part of the celebration for the soon-to-open Rolex headquarters on New York City’s Fifth Avenue.
IndependentsJul 01, 2026
Kristen Cannon of Valobra Master Jewelers Dies at 49The public relations professional is remembered for her benevolent generosity and unwavering commitment to those around her.
WatchesJun 30, 2026
Pokémon Fans Will Want to Catch This New G-Shock WatchThe new watch commemorates Pokémon’s 30th anniversary.
MajorsJun 30, 2026
Saks Global Emerges From Bankruptcy With New NameThe luxury retailer is now called Exemplar Luxury Group.
CollectionsJun 30, 2026
Jade Ruzzo’s New Collection Embodies the Art of Being a LadyThe “Lady” collection is a new take on old beauty standards with gemstone-adorned hair pins and combs, a compact mirror necklace, and more.
SourcingJun 30, 2026
Blue Nile Introduces Montana Sapphire CollectionThe new line is included in the e-tailer’s curation of jewelry celebrating America’s 250th anniversary.
GradingJun 30, 2026
AGS Opens 2026 Recertification ExamAll active members who earned their credential or designation before Dec. 1, 2025, are required to recertify.
CollectionsJun 29, 2026
Briony Raymond’s New Collection Is a ‘Carousel’ of Hard StonesThe new jewelry collection uses a colorful palette of onyx, malachite, tiger’s eye, mother-of-pearl, lapis, turquoise, and coral.
IndependentsJun 29, 2026
Look Inside Lee Michaels’ Revamped Mississippi FlagshipLee Michaels Fine Jewelry is celebrating 30 years in the Ridgeland, Mississippi community.
