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
IndependentsJun 05, 2026
Pennsylvania Jewelry Store To Close After 79 YearsJim Springer, owner of Dunkelberger’s Fine Jewelry, is heading into retirement.
SurveysJun 05, 2026
Consumers to Cut Back on Spending Amid Rising Prices, Survey Shows When conducting its May consumer confidence survey, The Conference Board asked extra questions about consumers’ budgeting strategies.
CollectionsJun 05, 2026
Rebel Jewelry’s Charm Symbolizes Perseverance for Pride MonthThe “Tunnel” charm, our Piece of the Week, celebrates Pride Month with its design inspired by hope and the light at the end of the tunnel.
Brought to you by
All Eyes on Gold Prices. Alternatives to Look For. And What to BEWARE of in VegasAs gold prices rise, today’s retailers are looking for alternatives at prices that will appeal to wider audiences.
SourcingJun 05, 2026
State of Diamonds: The Way Forward for Natural DiamondsThe jewelry industry is reassessing its positioning as Gen Z reshapes the retail landscape and lab grown continues to gain market share.
Weekly QuizJun 05, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
AuctionsJun 04, 2026
Treasures from Maurice Tempelsman’s ‘Marvelous’ Life Head to AuctionUp for auction at Sotheby’s, the collection of Tempelsman’s personal effects includes a Cartier Tank watch Jackie O. gifted him.
CollectionsJun 04, 2026
Buddha Mama to Spend the Summer in AspenThe Miami-based fine jewelry brand will host its first summer residency in the Colorado mountain town from June 5 to Aug. 23.
Brought to you by
How Modern Training Is Becoming a Competitive Advantage for Jewelry RetailersWith the trade and customer trust in mind, GIA® developed NextGem™ – on-demand training designed specifically for retail.
MajorsJun 04, 2026
AGS Honors Late Peter Yantzer, Holds Time Capsule CeremonyThe organization also announced its international board of directors for the 2026-2027 term.
MajorsJun 04, 2026
Neiman Marcus’ Downtown Dallas Store to Close in SeptemberSaks Global confirmed the closure this week, spelling the end for a store that’s been part of downtown Dallas for more than 100 years.
ColumnistsJun 03, 2026
Peter Smith: When Top Talent Leaves and What It Says About YouSmith discusses how managers should handle a top performer's exit, warning that a poor response could have a lasting impact.
WatchesJun 03, 2026
The 1916 Company Taking Pre-Owned Rolexes on the Road, AgainThe retailer is bringing Rolex Certified Pre-Owned watches to five U.S. cities in 2026 for collectors to see, try on, and purchase.
IndependentsJun 03, 2026
Jessica Alba Is the New Face of Gabriel & Co.The actress and entrepreneur stars in the jeweler’s new campaign that celebrates life’s quiet moments.
TrendsJun 03, 2026
State of Design: Only the Innovative Will SurviveThe price of gold has risen, affecting the number of pieces designers make, the materials they use, and how they position themselves.
FinancialsJun 02, 2026
Signet Jewelers’ Q1 Sales Up 2% As It Focuses on ‘Core Four’ The jewelry retailer is zeroing in on Zales, Jared, Kay Jewelers, and Blue Nile as it looks to create unique brand identities for each.
SourcingJun 02, 2026
Leader Appointed for Botswana’s Diamonds for Development Fund Dr. Akinwumi Adesina, a development economist, will head the fund created to help Botswana diversify its economy.
WatchesJun 02, 2026
Watch Industry Veteran James Marks Joins Sotheby’sSotheby’s has appointed the former Phillips executive as its global head of private sales and retail in its watches division.
AuctionsJun 02, 2026
Sotheby’s to Auction 10-Carat Blue Diamond, 1960s Harry Winston Necklace A private collection of five Paraíba tourmalines also will be up for sale at Sotheby’s High Jewelry auction in New York, scheduled for June 16.
IndependentsJun 02, 2026
State of Retail: 6 Things Retailers Should Know About Consumers TodayFrom Gen Z’s view of luxury to “doom spending,” these are the six consumer trends to note this year.
Events & AwardsJun 01, 2026
Design Atelier Brands Have a Big Night at Emotional Couture Design AwardsThe show started by honoring Mildred Marcano, ended with a tearful Beth Anne Bonanno, and recognized a dozen-plus designers in between.
SourcingJun 01, 2026
RapNet Rebranding as Rapaport TradeThe revamped online diamond marketplace will feature pricing intelligence and data-driven tools for more efficient buying and selling.
SourcingJun 01, 2026
Gemfields’ Higher-Quality Emerald Auction Achieves $26.8MThe miner said demand for higher-quality emeralds is stable, but there is notable caution in the market.
CollectionsMay 29, 2026
Cultus Artem’s Necklace Is the Oasis in Las Vegas’ DesertThe “River of Heaven” necklace, our Piece of the Week debuting at Couture, combines 26 salt and pepper diamonds spaced by Tahitian pearls.
IndependentsMay 29, 2026
Meet the 2026 Retailer Hall of Fame InducteesThis year’s inductees include second-, third-, and fourth-generation jewelers.
Events & AwardsMay 28, 2026
JCK Announces Jesse Itzler as 2026 Keynote SpeakerThe author, speaker, and entrepreneur will give his presentation, “Spiritual Billionaire,” on Saturday morning.
Events & AwardsMay 28, 2026
JCK Rocks To Ride With NellyThree-time Grammy award-winning artist Nelly is set to perform at the annual event at Tao Beach on Sunday night.
MajorsMay 28, 2026
Signet Jewelers to Buy The Clear Cut Signet will integrate the online-only, natural diamond-focused jeweler into Blue Nile, which it wants to position as a higher-end retailer.
