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
TrendsDec 03, 2025
Miley Cyrus Debuts Edgy Engagement RingFellow musician Maxx Morando proposed to the star with a chunky, cushion-cut diamond ring designed by Jacquie Aiche.
MajorsDec 03, 2025
Costco Joins Growing Wave of Retailers Suing for Tariff Refunds The retailer, which sells billions in fine jewelry and watches, is suing the Trump administration and U.S. Customs and Border Patrol.
SurveysDec 03, 2025
A Record 202.9M Shoppers Turned Out Thanksgiving WeekendBlack Friday is still the most popular shopping day over the five-day holiday weekend, as per the National Retail Federation’s survey.
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 03, 2025
Fabergé’s 'The Winter Egg' Achieves Record $30MThe historic egg, crafted for Russia's ruling family prior to the revolution, was the star of Christie’s recent auction of works by Fabergé.
Weekly QuizNov 20, 2025
This Week’s QuizTest your jewelry news knowledge by answering these questions.
FinancialsDec 02, 2025
Signet Jewelers’ Q3 Sales Up Amid Continued Focus on Lower Price PointsThe retailer offered more fashion jewelry priced under $1,000, including lab-grown diamond and men’s jewelry.
CollectionsDec 02, 2025
Briony Raymond Introduces First FragranceThe eau de parfum is held in a fluted glass bottle that mirrors the decor of the brand’s atelier, and its cap is a nod to its “Sloan” ring.
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.
SourcingDec 02, 2025
Petra Diamonds Elevates Interim CEOs to Permanent StatusVivek Gadodia and Juan Kemp, who’ve been serving as interim co-CEOs since February, will continue to lead the diamond mining company.
MajorsDec 02, 2025
Lee Krombholz Takes Over as Chair of MJSA Education FoundationIn addition, a slate of new officers and trustees were appointed to the board.
IndependentsDec 02, 2025
RJO Welcomes Its 1,200th Retail MemberWitt’s Jewelry in Wayne, Nebraska, is the organization’s new milestone member.
SourcingDec 02, 2025
Brendan Laurs Honored With 2025 Bonanno AwardLaurs is the editor-in-chief of Gem-A’s The Journal of Gemmology and an expert on the formation of colored gemstone deposits.
CrimeDec 01, 2025
Fourth Man Charged in Louvre Jewelry HeistThe man, who has a criminal history, is suspected of being the fourth member of the four-man crew that carried out the heist.
AuctionsDec 01, 2025
Christie’s Presents ‘Splendor & Style’ CollectionThe single-owner collection includes one of the largest offerings of Verdura jewels ever to appear at auction, said Christie’s.
IndependentsDec 01, 2025
Lustig Jewelers’ New Owner Is a Fellow Chicago JewelerMichael Helfer has taken the reins, bringing together two historic Chicago jewelry names.
MajorsDec 01, 2025
PGI Debuts Platinum-Filled Holiday Gift GuideThe guide features all-new platinum designs for the holiday season by brands like Harwell Godfrey, Ritani, and Suna.
FinancialsNov 26, 2025
Movado CEO Talks Tariffs, Growing Interest in Accessible Luxury WatchesDuring its Q3 call, CEO Efraim Grinberg discussed the deal to lower tariffs on Swiss-made watches, watch market trends, and more.
TrendsNov 26, 2025
Piece of the Week: Rosior’s Pumpkin RingRosior’s high jewelry cocktail ring with orange sapphires and green diamonds is the perfect Thanksgiving accessory.
IndependentsNov 26, 2025
Greenwich St. Jewelers Launches Colorful Holiday CampaignThe “Embrace Your True Colors” campaign features jewels with a vibrant color palette and poetry by Grammy-nominated artist Aja Monet.
MajorsNov 26, 2025
Serafino Consoli Names New VP of Sales, Brand Development for the AmericasLuxury veteran Alejandro Cuellar has stepped into the role at the Italian fine jewelry brand.
Events & AwardsNov 26, 2025
Grandview Klein Presents 4 Scholarships in NamibiaThe company gave awards to four students at the Namibia University of Science & Technology, including one who is a Grandview Klein employee.
IndependentsNov 25, 2025
Pearl Stringer Margaret Hoisik DiesShe is remembered as an artist who loved her craft and was devoted to her faith, her friends, and her family.
SourcingNov 25, 2025
Finestar Opens Diamond Manufacturing Facility in JohannesburgIt joins the company’s other manufacturing facilities globally, including in India, Botswana, and Namibia.
TrendsNov 25, 2025
Amanda’s Style File: Polka DotsThe polka dot pattern transcends time and has re-emerged as a trend in jewelry through round-shaped gemstones.
CrimeNov 25, 2025
Former Arizona AG Official Charged With Trafficking Stolen JewelryVanessa Hickman, 49, allegedly sold a diamond bracelet that was mistakenly sent to her home.
Events & AwardsNov 25, 2025
GIA Awards Susan Jacques With Its Highest HonorGIA’s former president and CEO was presented with the Richard T. Liddicoat Award for Distinguished Achievement.
Recorded WebinarsNov 24, 2025
Watch: Top Tips for Social Media EtiquetteSocial media experts spoke about protecting brand reputation through behaving mindfully online.
