SourcingAug 27, 2025
11,685-Carat Emerald Recovered From Zambia’s Kagem MineDubbed the “Imboo,” or “buffalo,” emerald, the rough gemstone is part of Gemfields’ latest emerald auction, which is taking place now.
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.”
The Latest
SurveysAug 27, 2025
Consumer Confidence Slips in August Amid Job, Income WorriesPlans for dining out, booking vacations, and buying big-ticket items were down.
CollectionsAug 27, 2025
Mined + Found’s New Collection Gets Playful The “Play” collection centers on nostalgic toys that have kinetic elements to carry playfulness and wonder into adulthood.
Brought to you by
Rallying Call for the Jewelry Industry on Tariffs and Other Key IssuesJewelers of America is leading the charge to protect the industry amidst rising economic threats.
CollectionsAug 26, 2025
Does Your Jewelry Stack Need a Snack?Designer Christina Puchi, the creative force behind CCWW Designs, has created charms and pendants based on iconic candies and crackers.
Weekly QuizAug 22, 2025
This Week’s QuizTest your jewelry news knowledge by answering these questions.
WatchesAug 26, 2025
Nick Jonas Gets Nostalgic in New Fossil CampaignThe Jonas Brothers star showed off new timepieces against the backdrop of his favorite spots in his home state of New Jersey.
IndependentsAug 26, 2025
Hinkamp Jewelers Celebrates 70 YearsThe family-owned jeweler in Fayetteville, North Carolina, is in the hands of the second generation.
Brought to you by
Taking the Moment Head On: How Rio Grande Champions the Present & Future of Fine JewelryAs a leading global jewelry supplier, Rio Grande is rapidly expanding and developing new solutions to meet the needs of jewelers worldwide.
ColumnistsAug 26, 2025
Back to School, Back to Style: Why August is Prime Time for Self-GiftingIn his latest column, Emmanuel Raheb shares tips for encouraging customers to treat themselves to new jewelry.
WatchesAug 25, 2025
London Jewelers Brings Rolex to Historic Hamptons HomeThe new stand-alone Rolex boutique is housed in the former Odd Fellows Hall, a landmark built in 1897.
CollectionsAug 25, 2025
Tennis Star Madison Keys Has the Perfect Necklace for the US OpenThe Brilliant Earth ambassador co-designed a diamond medallion featuring meaningful symbols.
TrendsAug 25, 2025
Amanda’s Style File: That’s a WrapWrap jewelry is more than just a trend; it’s the perfect motif for the coming season of layering, scarves, and pumpkin spice.
WatchesAug 25, 2025
WatchTime NY Show Returns for 10th Anniversary EditionThe three-day watch collector show, coming this October, will feature 44 exhibiting brands, as well as a new dinner experience.
GradingAug 22, 2025
Former Head of GIA India Promoted to Oversee Global Operations Sriram “Ram” Natarajan is now GIA’s senior vice president of laboratory operations and is based out of the lab’s headquarters in Carlsbad.
CollectionsAug 22, 2025
Piece of the Week: Retrouvaí’s ‘Diamond Vein Bond’ CollarThe one-of-a-kind collar represents the beauty of imperfection and the strength to rebuild.
MajorsAug 22, 2025
Kendra Scott Returns as CEO of Her Jewelry EmpireThree C-suite executives, including former CEO Tom Nolan, have resigned as part of what the company describes as a “transition.”
MajorsAug 21, 2025
Claire’s Finds Buyer, Could Save up to 950 StoresThe retailer, which recently filed Chapter 11, inked a deal to sell its North American business and intellectual property.
MajorsAug 21, 2025
Target Names New CEO as Sales Continue to Lag Target CEO Brian Cornell will step down in February and be replaced by the company’s chief operating officer, Michael Fiddelke.
Policies & IssuesAug 21, 2025
JA, IDMA Talk Tariffs With Execs in DC The group met with the president's senior trade advisor earlier this week to express the industry’s concerns about the effects of tariffs.
MajorsAug 21, 2025
Tiffany & Co. Pops Up at 2025 US OpenThe pop-up will display this year's Tiffany & Co. Singles Championship trophies along with a diamond-encrusted tennis racket and ball.
IndependentsAug 20, 2025
Bellman’s Jewelers Opens Second Store After COO's TikTok Takes OffThe New Hampshire-based store has expanded to Boston, propelled by the success of Alex Bellman’s TikTok page, “The Truthful Jeweler.”
CrimeAug 20, 2025
Another CA Jewelry Store Rammed With Car, RobbedThe latest incident happened Monday at a store in Oakland, California, continuing a pattern JSA first warned about last month.
WatchesAug 20, 2025
Oris Launches Watch Benefiting NYC Harbor Oyster RestorationThe new aqua green New York Harbor Limited Edition II is the watchmaker’s second collaboration with the Billion Oyster Project.
Events & AwardsAug 20, 2025
Take the Jewelers for Children ‘Trinity of Purpose’ ChallengeParticipants who attend any three Rings of Strength events will be awarded a special medal.
SourcingAug 19, 2025
Dubai’s Jemora Group Buys Diamond Miner LucapaThe investment company, founded by Dev Shetty, has acquired the struggling miner and its assets, including the Lulo mine in Angola.
ColumnistsAug 19, 2025
Peter Smith: The Arrival Fallacy and Jewelry RetailSmith shares wisdom he gleaned from a podcast he was listening to one morning while being walked by his dog, a Malshi named Sophie.
CrimeAug 19, 2025
Customs Seizes 7,300 Pairs of Fake ‘Alhambra’ EarringsThe counterfeit Van Cleef & Arpels jewels would have been worth more than $30 million if genuine.
