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.

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.”
The Latest

Sponsored by the Gemological Institute of America

The 2025 Australian Open champion is the jewelry brand’s first athlete ambassador.

The West Village jewelry boutique’s new shop-in-shop is the cornerstone of Nordstrom’s revamped jewelry hall.

The Seymour & Evelyn Holtzman Bench Scholarship from Jewelers of America returns for a second year.

This past year, the manufacturer said it recorded below-zero emissions per carat of natural diamond.


The brand’s “Golden Strada” statement necklace features round, marquise, and pear diamonds that sparkle like Fourth of July fireworks.

JSA’s Scott Guginsky provided a list of nine security measures jewelers should observe while locking up for the long weekend.

The countdown is on for the JCK Las Vegas Show and JA is pulling out all the stops.

Located on Rodeo Drive, the store’s design was inspired by Hollywood and Los Angeles culture.

The new location continues the brand’s celebration of its 25th anniversary.

The online watch marketplace’s “Time Is Our Thing” campaign highlights the importance of time.

She will oversee strategic planning, fundraising, industry partnerships, and the launch of the Gem Legacy Campus in Tanzania.

Working with Amazon’s Counterfeit Crimes Unit and law enforcement, Pandora helped to shut down a large-scale counterfeit network in China.

The jewelry company has closed its three California brick-and-mortar stores, as well as its online shop, for now.

The company is providing the opportunity for an FIT student to work alongside master diamond cutter Willie Lopez in its workshop.

He is remembered for his successful entrepreneurship, generosity, and dedication to his family.

The jewelry store chain has reportedly been struggling with costs related to tariffs as well as tough retail competition.

Welcome warm summer days with red hot rubies perfectly chosen as July’s birthstone.

Co-founders Afzal Imram and Lin Ruiyin brought their son’s story of a cosmic egg, toadstool, and railroad to life in their new collection.

The best time to prepare for the holiday season is right now, according to columnist Emmanuel Raheb.

This year’s winner is Morgan Keefe, who is currently studying at GIA to be a gemologist.

“The Jewelry Book” comes out this September.

The company is focused on modernizing the custom jewelry buying experience with e-commerce tools like product visualization and 3D styling.

Following its recent acquisition, the storied brand has updated its leadership team and regional managers.

AGS also named the recipient of its “Women in Leadership” scholarship.

The 20-karat yellow gold and diamond wrap ring is modeled after the Monstera plants in the garden of the brand’s Miami villa.

Rocksbox President Allison Vigil shared the retailer’s expansion plans, and her thoughts on opening stores in malls.