ColumnistsSep 05, 2025
Peter Smith: A Lasting Lesson From Maurice Tempelsman Smith recalls a bit of wisdom the industry leader, who died last week, shared at a diamond conference years ago.
GradingApr 02, 2018
GIA Finds Synthetic Ruby Layer on Natural Gemstones
Though a lab-grown layer is nothing new, the absence of one element suggests different growth methods.
In this picture, a portion of the near-colorless corundum seed is revealed in an area where the synthetic ruby overgrowth was cut away. Photo credit: Hollie McBride/GIA
Carlsbad, Calif.--The Gemological Institute of America’s New York lab recently had a gemstone submitted for identification it hasn’t seen before.
According to an article by Tyler Smith and Hollie McBride in the winter 2017 issue of “Gems & Gemology,” the lab received two loose oval mixed-cut red gems for identification. Upon testing, the stones revealed refractive indices slightly higher than normal for corundum.
Higher refractive indices have been reported before for chromium-diffused corundum, in which extra chromium is added during heating to enhance the color. So, the article states, to the naked eye, the stones simply appeared to be chromium diffused and displayed red color concentrations at the intersections of the facets.
But further microscopic examination revealed a thin layer, about 0.3 mm thick, of “synthetic overgrowth”—a layer of lab-grown ruby that gave the stone its color—with a natural, almost-colorless sapphire at the core.
The authors said the two stones looked similar to Lechleitner synthetic overgrowth emeralds, named for Johann Lechleitner, who pioneered the process of giving a near-colorless beryl seed its green color with a synthetic emerald overgrowth in 1960. (The GIA’s lab in Carlsbad, coincidentally, received a Lechleitner emerald for identification around the same time the rubies were submitted.) 
Lechleitner also experimented with ruby overgrowth on both synthetic and natural corundum seeds.
While his specimens contained a number of elements, the two rubies submitted to the GIA were missing one—molybdenum—indicating there were different growth conditions present, according to the G&G article.
It noted that while this isn’t the first report of synthetic ruby overgrowth on natural sapphire seeds, it is the first time material featuring such aspects has been submitted to its New York and Carlsbad laboratories for identification.
“The resurfacing of these vintage overgrowth synthetics shows that once a material is in the trade, it is here to stay,” Smith and McBride said.
More on Grading
The Latest
CollectionsSep 05, 2025
Piece of the Week: Jamie Turner’s ‘Victoria’ Necklace The “Victoria” necklace features a labradorite hugged by diamond accents in 18-karat yellow gold.
Policies & IssuesSep 05, 2025
Trump Takes Tariffs Case to the Supreme Court Two lower courts have moved to block the import taxes, which will remain in place as the legal battle continues.
Brought to you by
Rallying Call for the Jewelry Industry on Tariffs and Other Key IssuesJewelers of America is leading the charge to protect the industry amidst rising economic threats.
WatchesSep 05, 2025
Patrick Mahomes Is the New Hublot Brand AmbassadorThe Kansas City Chiefs quarterback shares Hublot’s dedication to pursuing greatness, the Swiss watchmaker said.
Weekly QuizSep 04, 2025
This Week’s QuizTest your jewelry news knowledge by answering these questions.
SourcingSep 04, 2025
Lucara Unveils Unusual 37-Carat Pink DiamondThe Type IIa stone, recovered from Botswana’s Karowe diamond mine last month, features unique coloration.
Brought to you by
Taking the Moment Head On: How Rio Grande Champions the Present & Future of Fine JewelryAs a leading global jewelry supplier, Rio Grande is rapidly expanding and developing new solutions to meet the needs of jewelers worldwide.
Events & AwardsSep 04, 2025
27 Can’t-Miss Converge Sessions, Events From sunrise yoga to tariffs talks, these are some events to check out at the upcoming inaugural event.
WatchesSep 04, 2025
Breitling Takes Its NFL Game to the Next Level Breitling is now the NFL’s official timepiece partner, a move that puts the brand in front of the millions of Americans who watch football.
Events & AwardsSep 04, 2025
The NYC Jewelry, Antique, & Object Show Returns in NovemberNYCJAOS is set for Nov. 21-23 in New York City’s Chelsea neighborhood.
SourcingSep 03, 2025
Gemfields Confirms Completion of Fabergé SaleU.S.-based investment company SMG Capital LLC is the new owner of the luxury brand.
MajorsSep 03, 2025
These Are the Nearly 300 Claire’s Stores Set to CloseA new court filing details the locations of the stores that will close, as well as the 830 that will remain open.
MajorsSep 03, 2025
Stuller Releases 2 New Catalogs The new catalogs are “Tools, Equipment, & Metals” and “Findings & Metals.”
TrendsSep 03, 2025
Amanda’s Style File: A Perfect BirthstoneSapphire’s variety of colors make it the perfect birthstone for September.
FinancialsSep 02, 2025
Lab-Grown Diamonds, Lower-Priced Fashion Jewelry Drive Signet Jewelers’ Q2 SalesThe retailer has raised its guidance after seeing total sales increase 3 percent in the second quarter, beating expectations.
MajorsSep 02, 2025
Birks CEO Jean-Christophe Bédos Steps DownNiccolò Rossi di Montelera, executive chairman of the board, was appointed as interim CEO.
MajorsSep 02, 2025
Harry Winston Opens Its Largest Flagship in JapanThe three-floor space also features the jeweler’s largest VIP salon in Japan and offers an exclusive diamond pendant.
CollectionsSep 02, 2025
Stephanie Gottlieb Debuts Silver Designs in ‘All Hours’ CollabThe collection is a collaboration between Stephanie Gottlieb Fine Jewelry and Oak and Luna, focusing on understated essentials.
AuctionsAug 29, 2025
Sotheby’s UAE Sale to Feature 32-Carat Fancy Vivid Orangy Pink DiamondThe highlight of a single-owner jewelry and watch collection, it’s estimated to fetch up to $7 million at auction this December.
FinancialsAug 29, 2025
Movado’s Q2 Sales Rebound Despite Tariff ImpactCEO Efraim Grinberg noted a resurgence in the fashion watch market.
CollectionsAug 29, 2025
Piece of the Week: Mark Davis’ ‘Bullseye’ Necklace The “Bullseye” necklace, with vintage bakelite and peridot, August’s birthstone, is the perfect transitional piece as summer turns to fall.
Supplier BulletinAug 28, 2025
Clientbook Is Helping Jewelers Turn Clienteling Challenges into Wins with Hands-On Training and CoachingSponsored by Clientbook
SourcingAug 28, 2025
Botswana Declares Public Health Emergency Amid Diamond Sales SlumpPresident Duma Boko addressed the country’s medical supply chain crisis in a recent televised address.
MajorsAug 28, 2025
Borsheims Names New Jewelry BuyerFormer Free People buyer Afton Robertson-Kanne recently joined the retailer.
IndependentsAug 28, 2025
Sissy’s Log Cabin Donates School Supplies to Memphis StudentsThe jeweler teamed up with two local organizations for its inaugural “Back to School and Bling” event.
EditorsAug 27, 2025
Taylor Swift’s Engagement Ring Is a Fairy Tale for Vintage Diamond CutsThe singer’s new bling, reportedly a natural old mine-cut diamond, is no paper ring.
