MajorsJun 26, 2025
Why Rocksbox Is Opening Stores As Signet Jewelers DownsizesRocksbox President Allison Vigil shared the retailer’s expansion plans, and her thoughts on opening stores in malls.
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
IndependentsJun 26, 2025
Penny Ruston Dies at 80 The creator of the WJA Chicago chapter is remembered as a champion for women in the jewelry industry and a loving grandmother.
SurveysJun 26, 2025
After Recovering in May, Consumer Confidence Dips in June The decline was consistent across age groups and almost all income groups, with tariffs and inflation still top of mind.
Brought to you by
Investing in the Next Generation of Bench JewelersThe Seymour & Evelyn Holtzman Bench Scholarship from Jewelers of America returns for a second year.
CollectionsJun 26, 2025
Jam Out With Sorellina’s Jimi Hendrix-Inspired JewelsThe “Playlist: Electric Dreams” collection brings lyrics from the musician’s song, “Little Wing,” to life through fine jewelry.
Weekly QuizJun 20, 2025
This Week’s QuizTest your jewelry news knowledge by answering these questions.
Events & AwardsJun 26, 2025
The Jewelry Symposium Is Looking for Speakers for 2026 EventThe event is set for May 16-19 in Detroit, Michigan.
IndependentsJun 25, 2025
Marissa Collections Opens in Nantucket as Legal Fight ContinuesThe Vault’s Katherine Jetter is accusing the retailer of using info she shared for a potential partnership to move into Nantucket.
Brought to you by
Jewelers of America is Headed to Las Vegas for JCK 2025The countdown is on for the JCK Las Vegas Show and JA is pulling out all the stops.
CrimeJun 25, 2025
Customs Nabs Another Big Shipment of Fake Cartier, Van Cleef JewelryAgents seized 2,193 pieces, a mix of counterfeit Cartier “Love” and “Juste Un Clou” bracelets, and Van Cleef & Arpels’ “Alhambra” design.
CollectionsJun 25, 2025
Splash into Karina Choudhrie’s Collection of Underwater Circus PerformersThe designer brought her children’s book, “The Big Splash Circus,” to life through a collection of playful fine jewelry characters.
Events & AwardsJun 25, 2025
JA Announces Impact Initiative Fund RecipientsThe trade association has chosen the recipients of the funding initiative it formed to foster the growth and sustainability of the industry.
SourcingJun 25, 2025
2025 AGTA Spectrum Awards Open for EntriesThe organization has also announced this year’s slate of judges.
IndependentsJun 24, 2025
Colorado Bench Jeweler Celebrates 50 Years With Local RetailerLori Tucker started at Williams Jewelers when she was 18 years old.
WatchesJun 24, 2025
Citizen’s New ‘Fantastic Four’ Watch Is Literally Super The “Marvel | Citizen Zenshin” watch is crafted in Super Titanium and has subtle nods to all four “Fantastic Four” superheroes on the dial.
MajorsJun 24, 2025
Tacori, QVC to Launch Exclusive Lab-Grown Diamond Jewelry CollectionThe “XO Tacori” collection was designed to blend luxury and accessible pricing.
GradingJun 23, 2025
GIA Names New President and CEO Pritesh Patel, the lab’s chief operating officer, will take over as president and CEO of GIA.
Recorded WebinarsJun 23, 2025
Watch: Top Trends at Couture, JCK Las Vegas 2025National Jeweler and Jewelers of America discuss the standout jewelry trends and biggest news to emerge from the shows this year.
SourcingJun 23, 2025
Diamond Producers, Organizations to Kick in Money to Promote Natural DiamondsSignatories to the “Luanda Accord” committed to allocating 1 percent of annual diamond revenue to the Natural Diamond Council.
Events & AwardsJun 23, 2025
Jose Hess Design Awards Celebrate 6 Jewelry DesignersThe winning designs captured the “Radiance” theme.
Events & AwardsJun 23, 2025
Gem Awards Now Accepting Nominations for 2026Nominations in the categories of Jewelry Design, Media Excellence, and Retail Innovation will be accepted through July 30.
TrendsJun 20, 2025
Dua Lipa Stays On-Trend With Chunky Engagement RingThe singer’s ring ticks off many bridal trends, with a thick band, half-bezel setting, and solitaire diamond.
TrendsJun 20, 2025
Piece of the Week: Yvonne Léon’s ‘Python Gold’ BraceletThe bracelet references vintage high jewelry and snake symbolism as a playful piece where a python’s head becomes a working belt buckle.
CrimeJun 18, 2025
7 Men Indicted in $100M Brinks Jewelry HeistThe heist happened in Lebec, California, in 2022 when a Brinks truck was transporting goods from one show in California to another.
AuctionsJun 18, 2025
Historic ‘Marie-Thérèse Pink’ Diamond Fetches $14M at Christie’sThe 10-carat fancy purple-pink diamond with potential links to Marie Antoinette headlined the white-glove jewelry auction this week.
AuctionsJun 18, 2025
16th-Century ‘Gresham Grasshopper’ Ring Sells for $56KThe historic signet ring exceeded its estimate at Noonans Mayfair’s jewelry auction this week.
CollectionsJun 18, 2025
Kirk Kara Celebrates 135 Years With New JewelsTo mark the milestone, the brand is introducing new non-bridal fine jewelry designs for the first time in two decades.
SourcingJun 18, 2025
Gemfields Sells 36-Carat Rough RubyThe gemstone is the third most valuable ruby to come out of the Montepuez mine, Gemfields said.
