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.”
Editors' Picks
Sponsored by
More on Grading
The Latest
WatchesSep 25, 2026
Smaller Rolex Watches Showing Strength on Secondary Market, Data ShowsFive of the 10 fastest-appreciating Rolex models on Bob’s Watches were Datejust 31 or Lady Datejust watches.
MajorsSep 25, 2026
Sherwood Family Buys Back Daniel’s Jewelers from Private EquityThe Sherwood family and AJS Creations CEO Tejas Shah purchased the jewelry chain back from Palladium Equity Partners.
Lab-GrownSep 25, 2026
Brilliant Earth Collabs with Elizabeth Taylor Estate on Jewelry Collection“The Elizabeth Taylor Collection” uses lab-grown diamonds and gemstones in contemporary designs inspired by the icon.
Brought to you by
Meet Gemology’s Next Generation Microscope: GIA® Gemolite® NXT Professional EditionExperience gemstones with greater precision and comfort than ever before.
TrendsSep 25, 2026
A Peek at Taylor Swift’s Game-Day DiamondsThe artist wore Dana Rebecca Designs’ marquise diamond-set gold hoops at the Chiefs game last Sunday. Now they’re our Piece of the Week.
Weekly QuizSep 25, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
CrimeSep 24, 2026
From Conclave: Security Measures Jewelers Should Be TakingJSA and Jewelers Mutual shared advice on spotting suspicious behavior, combatting cell phone jammers, and staying safe at home.
Brought to you by
Your Piece Could Be the One Editors Talk AboutSubmit your pieces for a chance to win in this year's competition.
AuctionsSep 24, 2026
8-Carat Blue Diamond Heads to UK Jewelry AuctionThe fancy light blue diamond is estimated to fetch up to $2.6 million at Elmwood’s next week.
TrendsSep 24, 2026
This New Jewelry Book Decodes the Secret Meaning in Victorian Jewelry“Secret Language of Victorian Jewelry” unveils the meaning behind the symbols, motifs, and gemstones used in Victorian-era jewelry.
Lab-GrownSep 24, 2026
Kira Jewels Opens B2B E-Commerce Portal for Lab-Grown Diamond Jewelry KIRAJewels.one gives retailers access to more than 500 SKUs of lab-grown diamond rings, earrings, necklaces, and bracelets.
TrendsSep 23, 2026
Holiday Diamond Jewelry Trends: Layered Looks, PersonalizationThis holiday season, look to pieces that will help to fill out customers’ everyday diamond jewelry wardrobe, experts say.
SourcingSep 23, 2026
Organization That Promotes Natural Diamond Rebrands for Third Time The Natural Diamond Council is now The Diamond Collective and has announced a new strategy under CEO Amber Pepper.
IndependentsSep 23, 2026
This Milwaukee-Area Jeweler Is Serving the 7CsPaul’s Jewelers sells coffee, chocolate, and cookies from a custom gold-wrapped trailer parked outside the store starting at 7 a.m.
MajorsSep 23, 2026
Kay Jewelers’ New Campaign Goes ‘All In’ on LovePart of its brand relaunch, the marketing around the campaign includes a contest involving a jacket set with 550 diamonds.
Events & AwardsSep 23, 2026
Tiffany & Co. Exhibition Opening at Arkansas Museum The curation, opening soon at the Crystal Bridges Museum of American Art, honors the jeweler’s heritage through a distinctly American lens.
CollectionsSep 23, 2026
Pucker Up for Pandora’s New Pat McGrath Jewelry CollabThe jewelry giant has partnered with the famed makeup artist to create a colorful new collection of charms and rings.
IndependentsSep 23, 2026
Texas Jewelers Association to Celebrate 120th AnniversaryThe association will mark the milestone at its convention next month.
IndependentsSep 23, 2026
Sissy’s Log Cabin’s ‘Back to School and Bling’ Event ReturnsThe jeweler donated school supplies to Memphis, Tennessee, students during the event combining basketball and mentorship.
MajorsSep 22, 2026
Foundrae’s Lawsuit Against Pandora Can Continue, Court RulesA federal judge denied Pandora’s motion to dismiss Foundrae’s claim for copyright infringement of its medallions.
ColumnistsSep 22, 2026
Peter Smith: Our Struggle With Emotional SellingPeople aren’t thinking rationally when they are buying luxury products, and we shouldn’t be selling them that way, Peter Smith writes.
IndependentsSep 22, 2026
Constance Polamalu Named to '40 Under 40' ListThe Baltimore Business Journal recognized the entrepreneur for her leadership in business and the jewelry industry.
Events & AwardsSep 22, 2026
NYCJAOS Returns for Autumn EditionThe four-day show is slated for Nov. 19-22 at the Metropolitan Pavilion in New York City’s Chelsea neighborhood.
AuctionsSep 21, 2026
Ultra-Rare Cartier Cheich Watch Sells for $3.4M Offered at Sotheby’s Hong Kong, the one-of-a-kind white gold watch now holds the title of most valuable Cartier wristwatch sold at auction.
MajorsSep 21, 2026
Longtime Industry Executive Pamela Bernstein-Gulla to RetireBernstein-Gulla has been working in the jewelry industry for 40 years, most recently as chief engagement officer for Hill & Co.
IndependentsSep 21, 2026
Bhindi Jewelers Moves Into New, Larger California StoreThe relocated Glendale store, now at The Americana at Brand, was designed to be a contemporary “timepiece haven” inspired by luxury resorts.
AuctionsSep 18, 2026
7.52-Carat Unheated Paraíba Tourmaline Sells for $1.3M at Sotheby’s The top lot of the auction house’s Hong Kong jewelry sale was an Art Deco Mauboussin necklace with ruby beads, which sold for $2 million.
