GradingJun 14, 2021
IGI Finds 6-Carat ‘Natural’ Diamond Is Actually Lab-GrownGradingJul 23, 2021
Lead Glass-Filled Lab-Grown Ruby Submitted to GIA
Though it’s unclear why someone would treat the material in that way, it’s important gemologists know it exists, the lab said.
A 3.53-carat lab-grown ruby treated with lead-glass filling (Photo by Diego Sanchez; © GIA)
Carlsbad, Calif.—GIA recently received a stone it rarely sees: a lead glass-filled lab-grown ruby.
According to a lab note from Forozan Zandi in the spring 2021 issue of “Gems & Gemology,” the stone was submitted to the GIA Carlsbad lab for identification.
Zandi said that while it’s common for the lab to receive lead glass-filled natural rubies, to their knowledge only one other lab-grown example has ever been submitted.
The recently submitted ruby was transparent to semi-transparent, oval mixed-cut, and weighed 3.53 carats.
GIA performed the standard gemological tests on the stone, finding that it showed the properties of a ruby, including a refractive index of 1.761–1.769, a birefringence of 0.008, a specific gravity of 4.01, a uniaxial optic figure, and a characteristic ruby spectrum via a spectroscope.
It also put the stone under magnification, which helped the lab confirm it was filled, according to the note.
With lead glass-filled corundum, the filling material has a refractive index very close to that of the host material to reduce the appearance of fractures. GIA said it’s effective and helps improve clarity of even very low-quality material to help make it marketable.
Fortunately, it’s also easily detected under magnification, the lab added.
The lab-grown ruby in question showed a couple of conclusive identifying characteristics for the treatment when put under the microscope: orange and blue flash effects and gas bubbles trapped in the fractures.
Magnification, however, didn’t reveal any inclusions that would indicate a natural or lab-grown origin.
But when it viewed curved growth lines in the DiamondView, which looks at surface fluorescence by illuminating with shortwave ultraviolet light, the lab saw the striae as chalky luminescent bands, confirming the stone was lab grown.
Ultimately, the lab note concluded: “While it is unclear why anyone would go to the trouble to treat a synthetic ruby with lead-glass filling, gemologists should be aware that such material does exist in the trade.”
Related stories will be right here …
According to a lab note from Forozan Zandi in the spring 2021 issue of “Gems & Gemology,” the stone was submitted to the GIA Carlsbad lab for identification.
Zandi said that while it’s common for the lab to receive lead glass-filled natural rubies, to their knowledge only one other lab-grown example has ever been submitted.
The recently submitted ruby was transparent to semi-transparent, oval mixed-cut, and weighed 3.53 carats.
GIA performed the standard gemological tests on the stone, finding that it showed the properties of a ruby, including a refractive index of 1.761–1.769, a birefringence of 0.008, a specific gravity of 4.01, a uniaxial optic figure, and a characteristic ruby spectrum via a spectroscope.
It also put the stone under magnification, which helped the lab confirm it was filled, according to the note.
With lead glass-filled corundum, the filling material has a refractive index very close to that of the host material to reduce the appearance of fractures. GIA said it’s effective and helps improve clarity of even very low-quality material to help make it marketable.
Putting the lab-grown ruby under magnification revealed high relief trapped gas bubbles and blue and orange flash effects. (Photomicrograph by Diego Sanchez, field of view 7.19 mm; © GIA)
Fortunately, it’s also easily detected under magnification, the lab added.
The lab-grown ruby in question showed a couple of conclusive identifying characteristics for the treatment when put under the microscope: orange and blue flash effects and gas bubbles trapped in the fractures.
Magnification, however, didn’t reveal any inclusions that would indicate a natural or lab-grown origin.
But when it viewed curved growth lines in the DiamondView, which looks at surface fluorescence by illuminating with shortwave ultraviolet light, the lab saw the striae as chalky luminescent bands, confirming the stone was lab grown.
Ultimately, the lab note concluded: “While it is unclear why anyone would go to the trouble to treat a synthetic ruby with lead-glass filling, gemologists should be aware that such material does exist in the trade.”
More on Grading
The Latest
MajorsDec 19, 2025
MadaLuxe Group Acquires Ippolita The luxury goods company said founder Ippolita Rostagno will remain at the brand’s helm.
MajorsDec 19, 2025
LVMH Names New Bulgari CEOLaura Burdese, who joined the Italian luxury brand in 2022, will take on the role in July.
EditorsDec 19, 2025
2025 Jewelry Superlatives: A Yearbook-Style Year in Review The National Jeweler editors revisit the most noteworthy industry happenings and design trends from 2025.
Brought to you by
Impacting Tomorrow TodayHow Jewelers of America’s 20 Under 40 are leading to ensure a brighter future for the jewelry industry.
AuctionsDec 19, 2025
Jean Schlumberger’s ‘African Cat’ Is Purr-Fection Need a gift for the cat lover who has everything? Look no further than our latest Piece of the Week.
Weekly QuizDec 18, 2025
This Week’s QuizTest your jewelry news knowledge by answering these questions.
AuctionsDec 18, 2025
Audemars Piguet Reclaims Historic Pocket Watch at AuctionIt purchased the “Grosse Pièce,” an ultra-complicated Audemars Piguet pocket watch from the ‘20s, for a record-breaking price at Sotheby’s.
Lab-GrownDec 18, 2025
Kira Jewels Debuts Custom Lab-Grown Diamond Jewelry ServiceThe lab-grown diamond grower now offers custom engagement and fashion jewelry through its Kira Custom Lab Jewelry service.
Brought to you by
Roseco Releases New Full-Line CatalogRoseco’s 704-page catalog showcases new lab-grown diamonds, findings, tools & more—available in print or interactive digital editions.
EditorsDec 18, 2025
Terry Chandler Looks Back on 40 Years of Opportunity, Change, and FriendsChandler got his start at Michelson Jewelers and has served as DCA president and CEO since 2001. He will retire at the end of the month.
WatchesDec 18, 2025
Bob’s Watches to Open Store in New York’s JFK AirportThe boutique is slated to open this week inside Terminal 8, offering pre-owned Rolex watches and more to international travelers.
Supplier BulletinDec 18, 2025
Cell Jammers Are Targeting Your Business. Here's How to Beat ThemSponsored by Digital Monitoring Products
CrimeDec 17, 2025
Man Pleads Not Guilty to Swallowing Fabergé PendantThe special-edition egg pendant ingested in a New Zealand jewelry store was recovered after a six-day wait.
EditorsDec 17, 2025
2025 Jewelry Rewind: The Best Piece of the Week PicksAssociate Editor Natalie Francisco plays favorites with Piece of the Week, selecting a standout piece of jewelry from each month of 2025.
CollectionsDec 17, 2025
Lucy Hale Stars in Jacquie Aiche’s Holiday CampaignThe “Love and Desire” campaign is inspired by the magic that follows when one’s heart leads the way, said the brand.
MajorsDec 16, 2025
Pandora’s New CEO Will Step Up EarlyBerta de Pablos-Barbier will replace Alexander Lacik at the start of January, two months earlier than expected.
AuctionsDec 16, 2025
Suzanne Belperron, JAR Shine in Sotheby’s First Auctions at New HQSotheby’s held its first two jewelry sales at the Breuer building last week, and they totaled nearly $44 million.
Events & AwardsDec 16, 2025
TJS Now Accepting Scholarship Applications for 2026Winners will receive free registration and lodging for its fourth annual event in Detroit.
ColumnistsDec 16, 2025
Beyond Unboxing: Creative Reveals to Drive Reach and EngagementHere are six ideas for making more engaging content for Instagram Reels and TikTok, courtesy of Duvall O’Steen and Jen Cullen Williams.
Events & AwardsDec 16, 2025
Diamonds Do Good Names 2026 Award RecipientsThe honorees include a notable jewelry brand, an industry veteran, and an independent retailer.
CrimeDec 15, 2025
Men Receive Life Sentences in Home Invasion Murder of Jeweler Carlos Jose Hernandez and Joshua Zuazo were sentenced to life without the possibility of parole in the 2024 murder of Hussein “Sam” Murray.
Policies & IssuesDec 15, 2025
Sara Yood Named Co-Chair of RJC Standards CommitteeYood will serve alongside Eduard Stefanescu, the sustainability manager for C.Hafner, a precious metals refiner in Germany.
IndependentsDec 15, 2025
M.S. Rau to Open Store in AspenThe New Orleans jeweler is also hosting pop-up jewelry boutiques in New York City and Dallas.
AuctionsDec 12, 2025
13.54-Carat Paraíba Tourmaline Sets Records at Christie’sSet in a Tiffany & Co. necklace, it sold for $4.2 million, the highest price and price per carat paid for a Paraíba tourmaline at auction.
MajorsDec 12, 2025
David Webb Reveals Ice-Cold Holiday Window DisplayThe jeweler’s “Deep Freeze” display showcases its iconic jewelry designs frozen in a vintage icebox.
CollectionsDec 12, 2025
Piece of the Week: Oscar Heyman’s Sphene RingTake luxury gifting to new heights this holiday season with the jeweler’s showstopping 12-carat sphene ring.
Events & AwardsDec 12, 2025
IGI Jewelry Design Contest Now Accepting SubmissionsThis year's theme is “Unveiling the Depths of the Ocean.”
TrendsDec 11, 2025
Pinterest 2026 Trend Report: Brooches, Bold Gold, Cool BlueIn its annual report, Pinterest noted an increase in searches for brooches, heirloom jewelry, and ‘80s luxury.
