SourcingMay 05, 2026
Doug Hucker Returns to His RootsFollowing decades of association leadership, the “semi-retired” colored gemstone expert is turning his focus to gemstone education.
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 & AwardsMay 05, 2026
AMNH to Showcase Famous Jewelry, Trophies in Sports HistoryThe museum’s new exhibition will feature one of Jesse Owen’s Olympic medals, Yogi Berra’s crown, Super Bowl rings, and more.
Events & AwardsMay 05, 2026
JIS Launches Brand Exposure ProgramThe new program provides access to media exposure and editorial opportunities for exhibitors and retailers.
Brought to you by
Discover Timeless Treasures: A Showcase of Antique Jewelry & Timepieces in Las VegasGain access to the most exclusive and coveted antique pieces from trusted dealers during Las Vegas Jewelry Week.
CollectionsMay 04, 2026
Melanie Georgacopoulos Turns Pearls Into Light for ‘Eclipse’ CollectionThe “Eclipse” jewelry collection captures the fleeting moment where light and shadow align though onyx, diamonds, and freshwater pearls.
Weekly QuizApr 30, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
ColumnistsMay 04, 2026
The Key Mindset for Better Trade Show BuyingBuying discipline at trade shows starts with clarity about your inventory levels, Smith writes.
CrimeMay 04, 2026
Pawn Shop Manager Shot, Killed in FloridaLazaro Rodriguez Vega was murdered inside Cash Out Gold and Silver in Fort Pierce. A 20-year-old man has been charged in the case.
Brought to you by
Las Vegas Antique Jewelry & Watch Show: Showcasing the Most Collectible Merchandise from Across the GlobeGain access to the most exclusive and coveted antique pieces from trusted dealers during Las Vegas Jewelry Week.
IndependentsMay 04, 2026
Zadok Jewelers, Austin Parks Foundation Support Wildflower PreservationA portion of every engagement ring sold in its Austin showroom will support the care and preservation of Austin’s wildflowers and green spaces.
TechnologyMay 01, 2026
Gemist, Saban Onyx Partner on Retailer-Focused Customization OfferingTheir partnership combines Gemist’s customization technology with Saban Onyx’s U.S.-based manufacturing capabilities.
SurveysMay 01, 2026
Consumer Confidence Inches Up in April Despite Rising Gas PricesRespondents were concerned about the Middle East conflict and how it will impact their finances.
CollectionsMay 01, 2026
A ‘Hidden Garden’ Emerges in Tiffany & Co.’s 2026 Blue BookOur Piece of the Week, the “Butterfly” necklace, showcases a 7.02-carat oval diamond set between diamond, platinum, and 18-karat gold wings.
ColumnistsApr 30, 2026
Peter Smith: A Sleazy Salesman and the Case for Regret Avoidance Smith uses a comment he overheard in the grocery store to remind retailers that their job is to inspire buying behavior, not just sell.
MajorsApr 30, 2026
Claire’s New Summer Campaign Is a Sensory Wonderland for Gen Alpha“A Girl SMR at Claire’s” celebrates girlhood through the five senses with stacked jewelry, slime toys, scented accessories, and ASMR.
AuctionsApr 30, 2026
Vintage Cartier Watch Crashes Through Records, Selling for $2MBelieved to be one of three made in 1987, the Cartier London Crash was hot at the “Shapes of Cartier” sale at Sotheby’s Hong Kong.
CrimeApr 30, 2026
Masked Group Uses Hammers, Pepper Spray in Texas Jewelry Store RobberyOfficials are looking for a group that robbed Marc Robinson Jewelers at an outlet mall in Round Rock, Texas, in broad daylight on April 21.
Supplier BulletinApr 30, 2026
OROAREZZO 2026: The B2B Event for Italian Excellence in Goldsmith, Jewelry and Silver ManufacturingSponsored by OROAREZZO International Jewelry Exhibition
TechnologyApr 29, 2026
The Thought Process Behind the Mother's Day Email Opt-OutSome retailers are taking a nuanced approach to marketing what can be a difficult holiday for many.
IndependentsApr 29, 2026
Dick Abbott to Retire From The EdgeThe Edge has announced its new CEO, as well as a new partnership with an investment firm focused on founder-led software businesses.
SourcingApr 29, 2026
De Beers’ Production Rises, Market Remains ‘Challenged’De Beers’ diamond production was up 17 percent in Q1, boosted by increased output at its mines in South Africa and Canada.
AuctionsApr 29, 2026
This'll Be the Day You Own John Wayne's RingA signet ring belonging to the Western film star of Hollywood’s Golden Age will be up for auction at Elmwood’s next month.
Policies & IssuesApr 28, 2026
Tariff Refunds: How to File, What to Expect Importers can submit claims now to receive money back for the IEEPA tariffs they’ve paid, with refunds expected to take up to 90 days.
IndependentsApr 28, 2026
This North Carolina Jeweler Is Passing the TorchThe owners of Gregory Jewelers in Morganton, North Carolina, are heading into retirement.
SourcingApr 28, 2026
Doug Hucker Retires From ICAThe colored gemstone industry leader is heading into retirement after four years as the association’s CEO.
SourcingApr 28, 2026
NDC Hires Tapestry Exec to Head Global Marketing Susie Dewey joins the Natural Diamond Council as its new chief marketing officer.
AuctionsApr 27, 2026
12 Years Later, the ‘Ocean Dream’ Diamond Resurfaces at Christie’sThe largest known fancy vivid blue-green diamond could fetch more than $12 million at its second auction appearance.
ColumnistsApr 27, 2026
Stop Treating Mother’s Day Like an AfterthoughtEmmanuel Raheb says jewelers need to start marketing early and make it easy for customers to pick a gift for mom.
