FinancialsMar 19, 2026
Signet Jewelers to Close 100 Stores, Shutter James Allen BannerThe jewelry retailer announced changes to its store network and brand portfolio during its fourth-quarter earnings call.
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
SurveysMar 19, 2026
NRF Forecasts 4% Retail Sales Growth in 2026From a weaker labor market to inflation, NRF Chief Economist Mark Mathews gave insight on what retailers can expect this year.
AuctionsMar 19, 2026
26-Carat Diamond Tops $1M at AuctionThe historic stone, which sold at Elmwood’s in London, is the largest white diamond to be offered on the U.K. market in more than a decade.
Brought to you by
Protect Your Customers and Your BusinessYou deserve to know what you are selling–to protect your customers as well as your business and your reputation.
Events & AwardsMar 19, 2026
JCK Rocks To Ride With NellyThree-time Grammy award-winning artist Nelly is set to perform at the annual event at Tao Beach in Las Vegas on May 31.
Weekly QuizMar 19, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
AuctionsMar 18, 2026
Collection of the ‘Severely Beautiful’ Lady Wardington Fetches $161KThe model and fashion editor’s gold evening bags were the top lots at the London sale, going for more than $25,000 each.
PodcastsMar 18, 2026
Episode 3: An Interview With Jewelry Designer Johnny NelsonFresh off winning the David Yurman Gem Awards Grant, Nelson discusses the ring that launched his career and his plans for the future.
Brought to you by
Is This You? Every Jeweler Has This Problem; We Have the Solution.Every jeweler faces the same challenge: helping customers protect what they love. Here’s the solution designed for today’s jewelry business.
SourcingMar 18, 2026
Lucara Recovers Nearly 37-Carat Blue DiamondThe “stunning” Type IIb stone was found via x-ray technology at its Karowe mine in Botswana.
MajorsMar 18, 2026
Stuller Releases New Edition of Jewelry Education Book“The Basics of Jewelry” has been updated to include modern topics and visuals.
Events & AwardsMar 17, 2026
The Best Moments From the 2026 Gem Awards Held just before the Oscars, the jewelry industry’s big awards show had its share of standout jewelry, gowns, and acceptance speeches.
SourcingMar 17, 2026
Cruzeiro Mine Debuts ‘Winter Tourmaline’The Brazilian mine’s new collection features cabochons in soft, muted shades like silver and lilac.
TrendsMar 17, 2026
Natalie Portman Is Tiffany & Co.’s New AmbassadorThe Academy Award-winning actress stars in Tiffany & Co.’s latest commercial, which debuted Sunday night during the Oscars.
MajorsMar 17, 2026
Kering Establishes Jewelry Division, Appoints CEOThe organizational change follows Kering’s promise of a transformation after declining sales in 2025.
WatchesMar 16, 2026
TAG Heuer Has a New CEOBéatrice Goasglas has been with TAG Heuer since 2018. She is the first woman to head the 166-year-old, LVMH-owned watch brand.
IndependentsMar 16, 2026
Ben Bridge Debuts New Honolulu BoutiqueThe store features the first in-store build for the jeweler’s in-house “Bella Ponte” bridal brand.
AuctionsMar 16, 2026
Bonhams Paris To Offer Antique, Signed Jewels The live fine jewelry auction will take place later this week, showcasing antique pieces, rare gemstones, and signed jewels.
CollectionsMar 13, 2026
A Trio of Jewels from the 3 Gem Award Nominees for Jewelry DesignOur Pieces of the Week honor the 2026 nominees for the Gem Award for Jewelry Design, Silvia Furmanovich, Cece Fein-Hughes, and Catherine Sarr.
WatchesMar 13, 2026
Citizen, Vera Wang to Launch Watch CollectionThe 24-piece watch collection is set to debut in spring 2027.
SourcingMar 13, 2026
Andrea Pooler Joins Third-Generation Diamond Company as COO Pooler, who has more than 25 years’ experience in jewelry, is now chief operating officer of Modani Jewels, Soham Diamonds, and SNJ Creations.
MajorsMar 13, 2026
24 Karat Club of New York’s Banquet to Return to Waldorf AstoriaThe reopening of the Waldorf Astoria means a homecoming for the industry group’s annual event, which will take place Saturday.
CollectionsMar 12, 2026
Jessica McCormack Sends Gold, Gemstones Into ‘Orbit’McCormack looked to the 19th century’s “golden age” of astronomy when designing her new celestial-themed collection.
Events & AwardsMar 12, 2026
Johnny Nelson Wins David Yurman Gem Awards GrantNelson will be honored as the inaugural grant winner at the Gem Awards gala on Friday.
TechnologyMar 12, 2026
Caratwise Launches, Names Former Signet Exec CEO The new smart design software allows jewelers to configure, price, and confirm a custom engagement ring in real time for in-store customers.
SourcingMar 12, 2026
Grandview Klein Opens New Factory in South Africa The 10,000-square-foot diamond manufacturing facility officially opened in late February and employs 50 people.
Events & AwardsMar 12, 2026
MJSA ‘Future of Jewelry Making’ Scholarship Applications OpenThe MJSA Education Foundation’s scholarships support students pursuing jewelry careers.
AuctionsMar 11, 2026
‘Spectacular’ 26-Carat Diamond Going Up for Auction in London The largest white diamond to come to market in the U.K. in more than a decade, the VVS1, I-color stone is expected to top $1 million.
