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
ColumnistsApr 09, 2026
Jewelry Demand Isn’t Stronger, Prices Are Just Higher Jewelers who misinterpret the state of the jewelry market risk employing the wrong retail strategy, cautions columnist Sherry Smith.
MajorsApr 09, 2026
Tiffany & Co. Promotes Nathalie Verdeille to SVP, Chief Artistic OfficerIn her newly expanded role, she will continue to oversee the jewelry category, as well as watches, home, and accessories.
WatchesApr 09, 2026
Jacob & Co. Rolls Out Its Sequel to ‘The Godfather’ Musical Watch“The Godfather II” watch plays two melodies from the mob film’s score, “The Godfather’s Waltz” and “The Godfather Love Theme.”
Brought to you by
Protect Your Customers and Your BusinessYou deserve to know what you are selling–to protect your customers as well as your business and your reputation.
Events & AwardsApr 09, 2026
JCK Announces Jesse Itzler as 2026 Keynote SpeakerOrganizers have also introduced the new JCK Talks Signature Series, as well as an offering of watch-focused workshops and lectures.
Weekly QuizApr 02, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
SourcingApr 09, 2026
AGA To Honor ‘Quiet Leadership’ With New AwardThe Alan Hodgkinson Medal recognizes gemologists who are consistently generous with their time and expertise.
WatchesApr 09, 2026
Oris Names New CEO, CFOThe Swiss watchmaker is changing up its executive leadership team as part of a restructuring.
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.
CollectionsApr 08, 2026
Hearts On Fire Celebrates 30 Years By Asking a QuestionThe “What’s Your Signature?” campaign invites women to think about how they see themselves.
SourcingApr 08, 2026
Sale of 42-Carat Blue Diamond Gives Petra a Boost in Q3The big diamond’s sale added to the company’s revenue though the market remains “challenging” overall, particularly for smaller goods.
Events & AwardsApr 08, 2026
AGS Confluence Returns with AI, Sustainability SessionsRob Bates of The Jewelry Wire will also moderate a panel on the state of the jewelry industry during the virtual event.
Events & AwardsApr 08, 2026
TJS to Honor 2 Longtime Former Stuller EmployeesThe Jewelry Symposium will honor two industry veterans with lifetime achievement awards at its upcoming May event.
TrendsApr 08, 2026
Amanda’s Style File: April’s Brilliant Birthstone With their durability, brilliance, and beauty, diamonds are the perfect stone for everyday birthstone jewelry.
MajorsApr 07, 2026
QVC Group’s Latest Filing Calls Its Future Into QuestionThe retailer failed to file its annual report on time and said it may issue a going concern warning.
ColumnistsApr 07, 2026
Peter Smith: A Tip to the Post Office on Workplace CultureSmith recounts a recent trip to the post office that included an uncomfortable, embarrassing, and public exchange between two employees.
CollectionsApr 07, 2026
Nerd Out Over Gemology Geek’s First Jewelry CollectionFounder Erica Silverglide has designed 35 colorful pieces set with fluorescing gemstones for the brand's first finished jewelry offering.
CollectionsApr 07, 2026
Ukrainian Jewelers Highlighted In New Book“Ukrainian Jewelry | Contemporary Jewelry and Art Jewelry from Ukraine” features 33 contemporary Ukrainian designers and studios.
CollectionsApr 06, 2026
Fope’s New Jewelry Debuts Are Golden“The Golden Now” campaign celebrates the here and now with the brand’s signature styles and a selection of its new pieces.
MajorsApr 06, 2026
Kecia Caffie, Corinne Bentzen No Longer With Signet JewelersSignet confirmed that Caffie, president of Zales and Banter, and Bentzen, who headed Blue Nile, have left the company.
CollectionsApr 06, 2026
Historian Tanzy Ward Pens Book on Black Victorians’ JewelryThe antique jewelry dealer talks about the importance of including Black Americans in jewelry history and preserving their stories.
SourcingApr 06, 2026
Gemfields Reports $51M Loss in 2025Both its mines faced challenges last year, from operational issues to disruptions in the market.
CollectionsApr 03, 2026
Taylor Swift’s ‘Elizabeth Taylor’ Video Puts Jewelry Front and CenterIconic pieces, like the Mike Todd Diamond Tiara, appear in the superstar’s new music video for her song inspired by the actress.
MajorsApr 03, 2026
Saks Global Says It Will Emerge From Bankruptcy This SummerThe luxury retailer, which went Chapter 11 in January, announced Thursday that it has secured $500 million in exit financing.
Events & AwardsApr 03, 2026
JCK Luxury, NouvelleBox Partner on New Designer BallroomThe NouvelleBox ballroom will feature independent jewelry designers, including Lene Vibe, Wyld Box Jewelry, and Kiaia Limited.
CollectionsApr 03, 2026
Buddha Mama Brings Its ‘Moon’ Locket To DallasThe one-of-a-kind locket, our Piece of the Week, opens to reveal three hidden images to keep close to your heart.
MajorsApr 02, 2026
Pandora Opens New Canadian Distribution Center Amid Tariff ConcernsThe new facility was also designed to better serve its growing customer base in Canada.
TrendsApr 02, 2026
Michelle Yeoh Fronts New Mikimoto Campaign The campaign is a tribute to the year 1893, when Kokichi Mikimoto created the world’s first cultured pearl.
