GradingNov 17, 2022
GIA Labs Report Receiving 2 Moissanites Submitted as Diamonds GradingDec 14, 2022
GIA Sees ‘Unusual’ Color Change in Sapphires During Stability Testing
Some sapphires gain orange or yellow coloration when exposed to incandescent light, according to a recent lab note.
A 3.54-carat padparadscha sapphire submitted to the GIA laboratory underwent a color stability test, during which time its orange color increased. If left in the dark for a while, the color could become less orange or straight pink, GIA said. The lab said this stone would be called a padparadscha sapphire because the pink-orange color seen after the stability test (far right) fits that range. (Photo credit: Diego Sanchez)
Carlsbad, Calif.—In color stability testing of sapphires, the Gemological Institute of America has noticed an “unusual” color change, according to a recent Lab Note.
GIA has performed color stability tests on some sapphires for decades but recently started using the test to identify pink sapphires that have a temporary change of color.
According to the Lab Note written by Aaron Palke, Shane McClure, and Nathan Renfro, some pink sapphires, when exposed to UV light, temporarily change into the orangey pink to pinkish orange hue range of padparadscha sapphires or can become even more orange in appearance.
The change can also happen when these same sapphires are exposed to sunlight, although it takes longer, GIA noted.
The unstable orange component will fade away with a few hours of exposure to “intense incandescent illumination,” GIA said, and return the color to pink.
In these cases, GIA will only call the sapphire “padparadscha” if the color fits within the range after the stability test.
But, recently, GIA has also observed sapphires reacting to the color stability test by gaining orange or yellow coloration after being exposed to incandescent light; some pink sapphires shift to a padparadscha color or pure orange, and the saturation of pale yellow sapphires can increase.
If these sapphires were to be stored in the dark for a while, they would fade to the ground state, which is typically purplish pink, pink, or pale yellow, GIA reported.
Further exposure to light containing UV, including sunlight, would lead to the sapphire again showing the orange or yellow color.
Importantly, GIA said the gaining of color during the stability test has been observed in all the color-unstable sapphires used in its research project after they faded to their ground state under intense LED light or when left in the dark.
It added: “While this is not part of GIA’s normal testing procedures for color-unstable sapphires, it is expected that any color-unstable sapphire could behave similarly and gain color during the stability test to some extent, depending on its initial color (e.g., if left in the dark for extended time).”
It also noted that color instability might not always be identified if the starting color is close to the color created when it’s exposed to incandescent light.
Its results, it said, bring up the questions of how gem labs should determine the color of sapphires that change after UV light exposure and which color should be used to describe them.
GIA said the colors it saw after performing the tests were very similar to what it observed after the stones were exposed to daylight, which is how they would appear if they were set and worn often.
Because of this, and in an effort to create a “consistent and easily accessible standard,” the authors said GIA will indicate on its colored stone reports the color after the incandescent light stability test is performed.
This will be the case no matter if a sapphire loses or gains yellow or orange color during the test, GIA added.
Full results of its research in the area will be published in its Gems & Gemology journal soon.
To see full issues and articles, visit GIA.edu.
Editors' Picks
Sponsored by
More on Grading
The Latest
CollectionsAug 28, 2026
Dolly Parton Would Have Loved This Butterfly Necklace This Buddha Mama butterfly is our Piece of the Week honoring the legend, who embraced the beautiful insect as her symbol.
SourcingAug 28, 2026
Gareth Penny to Give Opening Speech at CIBJO Centenary CongressThe former De Beers CEO, and perhaps its next owner, will be a featured speaker at the event, slated for Sept. 4-7 in Italy.
IndependentsAug 28, 2026
Day’s Jewelers Honored With 3 Workplace AwardsThe employee-owned jeweler was named a “Best Place to Work” in Maine, New Hampshire, and for women.
Brought to you by
Your Piece Could Be the One Editors Talk AboutSubmit your pieces for a chance to win in this year's competition.
CollectionsAug 27, 2026
Pandora Expands ‘Talisman’ Collection as Lawsuit Continues The second iteration of the jewelry collection was inspired by the zodiac and the four elements: earth, water, air and fire.
Weekly QuizAug 27, 2026
This Week’s QuizTest your jewelry news knowledge by answering these questions.
SourcingAug 27, 2026
OFAC Renews License Allowing Import of ‘Grandfathered’ Russian Diamonds General License 104B supersedes General License 104A, which was set to expire on Sept. 1.
CrimeAug 27, 2026
Customs Seizes Nearly 900 Pieces of Counterfeit JewelryThe package, intercepted in Indianapolis, contained fake Cartier, Tiffany & Co., and Van Cleef and Arpels jewelry.
Brought to you by
Why More Jewelry Retailers Are Hosting Turnkey Estate Buying EventsRetailers are seeking new ways to attract customers, increase traffic, and create revenue – Estate buying events are a popular solution.
IndependentsAug 27, 2026
Jessica McCormack to Open First West Coast StoreThe new location in Costa Mesa, California, marks the brand’s second store in the United States and fourth standalone location worldwide.
FinancialsAug 27, 2026
Movado’s Q2 Sales Up As Younger Consumers Take Interest in WatchesThe fashion watch category was once threatened by the Apple Watch, but consumers are now opting for new wearables, said Movado’s CEO.
SurveysAug 26, 2026
5 Jewelry Insights From The RealReal’s Resale ReportThe report delves into trending styles, the most popular jewelry brands by city, and why Belle Époque jewelry could be the next big thing.
Lab-GrownAug 26, 2026
AGTA Now Requiring Members to Call Lab-Grown Gems ‘Synthetic’The association added the requirement to its revised "Code of Ethics" and released the 17th edition of its “Gemstone Information Manual.”
SurveysAug 26, 2026
Consumer Confidence Dips in August Amid Anticipatory Anxieties Respondents were concerned about the future of the labor market and their income as well as the rising prices of gas and groceries.
TrendsAug 26, 2026
Boucheron’s New Campaign Celebrates Its ‘Question Mark’ NecklacesThe campaign highlights the asymmetrical high jewelry necklace style that the jeweler first created in 1879.
Events & AwardsAug 26, 2026
Harry Winston Exhibition to Open in ShanghaiIt will explore the life of “The King of Diamonds” and showcase more than 165 creations from the brand.
CrimeAug 25, 2026
Florida Woman Scammed Out of $1.5M in Jewelry, Precious MetalsTwo suspects have been arrested in connection with the complex phone scam.
ColumnistsAug 25, 2026
Proof Before Purchase: The Gen Z Way to BuyIn her first column for National Jeweler, Jennifer Shaheen asks jewelers if they know how to connect with the next generation of consumers.
Events & AwardsAug 25, 2026
SSEF Opens 2026 Applications for Gemology Education ScholarshipsThe annual awards cover tuition for an on-site educational course at the Swiss lab, as well as flights and lodging.
TrendsAug 25, 2026
Brent Neale Celebrates Blackberry Farm’s Anniversary With JewelryThe jeweler partnered with the Tennessee resort to honor its 50th anniversary with limited-edition blackberry pendants and earrings.
EditorsAug 24, 2026
Q&A: Reeds Jewelers VP Genna Zimmer on 80 Years in BusinessThe third-generation jeweler shared how the North Carolina retailer is celebrating this milestone and the love story that started it all.
Events & AwardsAug 24, 2026
Rio Grande, MetalWerx Host Argentium Silver WorkshopThe class, led by renowned metalsmith Cynthia Eid, highlighted Argentium silver as an alternative to gold amid high prices.
Events & AwardsAug 24, 2026
JIS Miami Opens Fall 2026 RegistrationThe show is slated for Oct. 16-19 at the Miami Beach Convention Center.
CollectionsAug 24, 2026
Francesca Villa Honors Napoleon, His Empresses In New CapsuleThe “Empresses” capsule uses 19th-century medals depicting Napoleon, Joséphine, and Marie-Louise across five one-of-a-kind pieces.
SurveysAug 21, 2026
These Are 2026’s Hottest Retailers, Says NRFThe retailers at the top of the list offer affordable products and fun, discovery-fueled experiences.
WatchesAug 21, 2026
Bremont Names Former Vacheron Constantin Exec CMODaniel Bing was formerly the marketing director for the Americas at Vacheron Constantin.
CollectionsAug 21, 2026
Bijules, Kamyen Serve Up ‘Topspin’ Tennis Bracelet Ahead of US OpenIn our Piece of the Week, the designers reimagine the tennis bracelet with green enamel wrapped around a strand of “Desert Diamonds.”
PodcastsAug 20, 2026
Episode 8: Diamond Industry Update With David Bonaparte & Ronnie VanderLindenThe industry veterans join the podcast to discuss diamond marketing, the FTC Jewelry Guides, and lobbying for lower tariffs.
