MajorsMar 05, 2026
Registration Opens for CIBJO Centenary CongressThis year’s annual congress, which will mark the confederation’s 100th anniversary, will take place this fall in Italy.
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 & AwardsMar 05, 2026
AGS Announces Conclave 2026 Speaker LineupThe annual event will be held in Orlando, Florida, from Sept. 14-17.
TrendsMar 05, 2026
Engagement Ring Trends 2026: What’s In, and WhyWe asked a jewelry historian, designer, bridal director, and wedding expert what’s trending in engagement rings. Here’s what they said.
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.
TrendsMar 05, 2026
Caitríona Balfe Fronts Only Natural Diamonds CoverThe “Outlander” star modeled for the digital cover of the magazine’s spring issue, which features a story on her relationship with jewelry.
Weekly QuizFeb 26, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
MajorsMar 04, 2026
Michael M Opens First StoreBeverly Hills was chosen as the location for the brand’s first store, designed as a “private residence for modern monarchs.”
Policies & IssuesMar 04, 2026
Luxury Brands Temporarily Shutter Middle East StoresKering, Apple, and other retailers have reportedly temporarily closed stores in the Middle East region in light of the recent conflicts.
Brought to you by
DCA Enters a New Chapter in Jewelry EducationWith refreshed branding, a new website, updated courses, and a pathway for growth, DCA is dedicated to supporting retail staff development.
Events & AwardsMar 04, 2026
JIS Miami Spring Show to Feature New Gifts Pavilion, Pop-Up Trends TalksNearly half of buyers are prioritizing silver and fashion collections this season, organizers said.
TrendsMar 04, 2026
Spinelli Kilcollin Rides Free In Year of the Horse CampaignThe “Live Now. Polish Later.” campaign features equestrians wearing the brand’s jewels while galloping across the icy plains of Kazakhstan.
MajorsMar 04, 2026
LeachGarner Names New Brand DirectorThe precious metals provider has promoted Jennifer Ashworth to the role.
Events & AwardsMar 03, 2026
Johnny Nelson Wins David Yurman Gem Awards GrantNelson will be honored as the inaugural grant winner at the Gem Awards gala on March 13.
SourcingMar 03, 2026
7 Trends That Could Define the Diamond Industry’s FutureExperts from India weigh in the politics, policies, and market dynamics for diamantaires to monitor in 2026 and beyond.
MajorsMar 03, 2026
Swiss Refiner Completes Acquisition of Gannon & ScottThe American precious metals refiner’s day-to-day operations remain the same post-acquisition.
TrendsMar 03, 2026
Amanda’s Style File: AquatopiaThese aquamarine jewels channel the calming energy of the March birthstone.
Events & AwardsMar 03, 2026
AGTA Adds Another New Category for SpectrumThe “Innovative Design” category and award will debut in the Spectrum division of this year’s AGTA Spectrum & Cutting Edge Awards.
SurveysMar 02, 2026
Consumer Confidence Edges Up in FebruaryConsumers were somewhat less worried about the future, though concerns about rising prices and politics remained.
Events & AwardsMar 02, 2026
JVC to Honor Rebecca Foerster at Annual LuncheonFoerster is this year’s Stanley Schechter Award recipient.
Events & AwardsMar 02, 2026
JFC Names 2026 ‘Facets’ Honorees Sponsorships and tickets to the annual fundraising event, set for May 31, are available now.
CrimeFeb 27, 2026
Man Charged in Murders of Father, Son Jewelers in ChicagoChicago police and members of the U.S. Marshals Service tracked down the 35-year-old suspect earlier this week in St. Louis.
SourcingFeb 27, 2026
South African Diamond Mine Closes Amid Search for Missing WorkersOwners of the Ekapa Mine reportedly filed for liquidation about a week after a mudslide trapped five workers who have yet to be found.
MajorsFeb 27, 2026
Jewelers Mutual to Donate $10M to Savannah College of Art and DesignA 10-year alliance has also begun to address the shortage of bench jewelers through scholarships, enhanced programs, and updated equipment.
CollectionsFeb 27, 2026
Renato Cipullo Turns Gold into HardstonesThe “Splendente” collection has evolved to feature hardstone letter pendants, including our Piece of the Week, the onyx “R.”
AuctionsFeb 26, 2026
Noonans to Auction Lady Wardington’s JewelryThe jewelry collection belonged to “one of society's most glamorous and beautiful women of the mid-20th century,” said the auction house.
SourcingFeb 26, 2026
Anglo American CEO Gives Insight Into De Beers SaleThe update came as Anglo took its third write-down on the diamond miner and marketer, which lost more than $500 million in 2025.
ColumnistsFeb 26, 2026
Practical Ways Jewelers Can Leverage AI in 2026Emmanuel Raheb discusses the rise of “GEO” and the importance of having well-written, quality content on your website.
CrimeFeb 26, 2026
Three Sentenced in California Jewelry HeistEach received around four years for burglarizing a jewelry store and a coffee shop in Simi Valley, California, last May.
