CollectionsApr 17, 2025
John Hardy, Athena Calderone Partner on Art Deco Decor-Inspired CollectionInterior designer Athena Calderone looked to decor from the 1920s and 1930s when crafting her first fine jewelry collection.
GradingSep 11, 2013
New treatment could damage conch pearls
A Swiss gemology laboratory is warning the trade about a new coating being applied to the surface of conch pearls that does visible, nearly irreversible damage to them.
This photo, taken by Swiss Gemmological Institute Director Michael Krzemnicki, shows a conch pearl that has been heavily damaged by a new, unstable artificial resin coating being applied to the gemstones.
Basel--A Swiss gemology laboratory is warning the trade about a new coating being applied to the surface of conch pearls that does visible, nearly irreversible damage to them.
According to a news release from the Swiss Gemmological Institute (SSEF), a client recently submitted a necklace of conch pearls set between alternating seed pearls and diamond briolettes. The client said the piece had been worn only occasionally over the past few months, spending most of that time in his safe, and had been handled with the appropriate care.
Still, some of the pearls showed visible signs of damage. They were corroded with a whitish crust covering their surface.
A scanning electron microscopic analysis of the conch pearls revealed that they had been coated by a carbon-rich layer, i.e., an artificial resin. SSEF Director Michael Krzemnicki said that it is the lab’s presumption that the de-gassing of the coating caused the corrosion of the underlying conch surface.
“This process, in the end, results in the precipitation of a whitish encrusting on the surface. It seems that only a thorough reshaping and re-polishing can remove the damage,” he said.
When SSEF first examined the necklace, it appeared that the surface alteration had not affected all of the conch pearls. Further study, however, revealed that the coating alters the conch pearls in stages. They begin looking dull, then move to having distinctly altered (whitened) surfaces and, finally, become heavily encrusted with whitish precipitates.
According to the lab, Raman spectrometry is the preferred method for detecting this treatment. Even coated conch pearls that are visually still “perfect” display a very strong and characteristic broad luminescence band that is not present in uncoated conch pearls.
Krzemnicki said the lab has added this testing to its standard analytical procedures for conch pearls. On its reports SSEF will describe these stones as, “treated conch pearl,” with this additional statement: “Indications of surface coating. This coating is not stable and may deteriorate the conch surface in the course of time.”
He said one the dangers of this new treatment is that it might begin to show its effects only after a piece of jewelry is sold to a private client, which could, in turn, impact the consumer’s confidence in pearls and the jewelry trade in general.
“By clearly labeling this new and unstable treatment on our reports, we are determined to support the trade to
take the necessary measures against this new threat and to prevent a further infiltration of these coated conch pearls into the market,” Krzemnicki said.
More information about pearls and pearl treatments is available on SSEF.ch. The lab also has an advanced pearl course online.
More on Grading
The Latest
FinancialsApr 17, 2025
Movado Group to Increase Prices to Offset Tariffs ImpactDuring a call about its full-year results, CEO Efraim Grinberg discussed how the company is approaching the uncertainty surrounding tariffs.
Lab-GrownApr 17, 2025
NDC Launches Its Diamond Learning CenterThe free program provides educational content for jewelry salespeople and enthusiasts to learn or refresh their diamond knowledge.
Policies & IssuesApr 17, 2025
Jewelers of America Requests Tariffs Testimonials from MembersThe feedback will be used to prepare other jewelers for the challenges ahead, the organization said.
Weekly QuizApr 18, 2025
This Week’s QuizTest your jewelry news knowledge by answering these questions.
TechnologyApr 17, 2025
Technology Therapy Group Expands AI Training for Jewelry RetailersThe online sessions are designed to teach jewelers to use AI tools like ChatGPT and Claude to grow their business.
IndependentsApr 16, 2025
Catbird Expands to ChicagoThe opening marks the jewelry retailer’s first location in the Midwest.
Brought to you by
The Heart of the Industry: Giving Bench Jewelers the Recognition They DeserveBench jewelers spend years honing their skills, Jewelers of America’s Certification validates their talents.
CollectionsApr 16, 2025
Foundrae’s First Commitment Jewelry Collection Unites Through LoveThe “United in Love” collection offers tangible mementos of hearts entwined with traditional and non-traditional commitment heirlooms.
IndependentsApr 16, 2025
Indiana Jeweler to Host Black Jewelry Designer Pop-UpRobert Goodman Jewelers will hold a “Black Jewelry Designers and Makers” event on April 27.
MajorsApr 16, 2025
WJA Announces Board Members, New Chicago Chapter PresidentThe announcements follow a tumultuous start to 2025 for WJA, which saw a wave of resignations following controversial statements about DEI.
EditorsApr 15, 2025
Tariffs: What We Know Right Now Editor-in-Chief Michelle Graff answers questions about how the new taxes levied on countries like India and China will impact the industry.
EditorsApr 15, 2025
Q&A: Bogolo Joy Kenewendo on Making Deals, Marketing DiamondsKenewendo, Botswana’s minster of minerals and energy, discusses closing the deal with De Beers and the work that was missed along the way.
AuctionsApr 15, 2025
23-Carat ‘Golconda Blue’ Heads to AuctionThe historic fancy vivid blue diamond set to headline Christie’s Geneva sale next month could sell for up to $50 million.
FinancialsApr 15, 2025
LVMH’s Q1 Sales Slip 2 PercentLVMH CFO Cécile Cabanis also discussed the effects of tariffs so far.
CrimeApr 15, 2025
Jon Hamm Plays a Jewel Thief on Apple TV+The “Mad Men” and “The Morning Show” star steals jewelry, art, and handbags from his wealthy neighbors in “Your Friends & Neighbors.”
SourcingApr 15, 2025
Diamond Club West Coast Names 2025 BoardThe organization has reelected Kalpesh Jhaveri as president.
FinancialsApr 14, 2025
Movado to Restate Years of Financials Due to ‘Misconduct’ in Dubai An investigation found that the former managing director of Movado’s Dubai branch overstated and prematurely recorded sales.
CollectionsApr 14, 2025
Sauer Embraces Emptiness Through ‘Ma’ CollectionThe collection pays tribute to the Japanese philosophy of Ma, studying balance, stillness, and the interplay between presence and absence.
IndependentsApr 14, 2025
Illinois Jeweler Closing After 45 YearsMari Lou’s Fine Jewelry in Orland Park, a suburb of Chicago, is closing its doors.
AuctionsApr 11, 2025
Piece of the Week: A Replica of Princess Grace’s Wedding EarringsThese earrings by Van Cleef & Arpels, featuring the same design as a pair worn by Princess Grace, are up for auction at Woolley & Wallis.
Recorded WebinarsApr 11, 2025
Watch: Top Tips for Saving Time With AITwo experts share how artificial intelligence tools can help retailers run a more efficient business.
SourcingApr 11, 2025
Mikimoto Names New President, CEO for U.S. DivisionKentaro Nishimura, who has been with the pearl company since 1997, has been promoted to president and CEO of Mikimoto America.
WatchesApr 11, 2025
Bulova Documentary Now on Amazon Prime“America Telling Time: 150 Years of Bulova” explores the storied history of the American watchmaker.
Policies & IssuesApr 10, 2025
Trump Presses Pause on Higher Tariffs for 90 DaysAn across-the-board tariff of 10 percent remains in place for all U.S. trading partners, except China.
MajorsApr 10, 2025
Brilliant Earth Taps Influencers, Their Moms for Mother’s Day CampaignBrigette Pheloung and Tania Sarin, and their mothers, star in the campaign wearing medallions they co-designed.
MajorsApr 10, 2025
Pary LeVian, Matriarch of the LeVian Family, Dies at 96LeVian is remembered for her unwavering commitment to her family, community, and helping others.
