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
Lab-GrownMar 06, 2026
Charles & Colvard Files for Bankruptcy, Citing Price PressuresIncreased competition, falling lab-grown diamond and moissanite prices, and the rising cost of gold took a toll on the moissanite maker.
CollectionsMar 06, 2026
Zome’s ‘Solara’ Earrings Embody Celestial BeautyThe earrings, our Piece of the Week, feature pink tourmalines as planets orbiting around an aquamarine center set in 18-karat rose gold.
MajorsMar 06, 2026
Pomellato’s 2026 IWD Campaign Spotlights Economic Abuse“The Price of Freedom” campaign video for International Women’s Day confronts the quiet violence of financial control.
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.
Policies & IssuesMar 05, 2026
Tariffs to Increase to 15% This Week, Treasury Secretary Says Also, a federal judge has ordered that companies that paid tariffs implemented under the IEEPA are entitled to refunds.
Weekly QuizMar 05, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
CollectionsMar 05, 2026
Common Era Honors ‘Difficult Women’ in CollectionThe ever-growing collection, which just expanded with the addition of Olga of Kyiv, features cameos of 12 women from history.
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
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 05, 2026
AGS Announces Conclave 2026 Speaker LineupThe annual event will be held in Orlando, Florida, from Sept. 14-17.
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.
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.
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.
EditorsMar 04, 2026
Q&A: Brilliant Earth’s CEO on the New Beverly Hills StoreBeth Gerstein discusses the vibe of the new store, what customers want when fine jewelry shopping today, and the details of “Date Night.”
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.
EditorsMar 02, 2026
Jewelry at the Actor Awards: Reimagining Hollywood GlamourDiamond jewelry was the star of the event formerly known as the SAG 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.
