SourcingMay 09, 2022
First Diamonds from Sierra Leone’s Tongo Mine Coming to MarketSourcingMay 17, 2022
A New Source in Tanzania Is Producing Cobalt-Blue Spinel
The stones come from a deposit close to Mahenge and have been on the market for several months.
Examples of the cobalt-blue spinel from Tanzania (Image courtesy of Mahenge Gems)
New York—Tanzania’s Mahenge region is known in the gem world for its beautiful red and pink spinel, but the area has begun producing another color recently—cobalt blue.
The newly discovered deposit is about 12.5 miles southeast of Mahenge.
The spinel started appearing on the market late last year, according to wholesaler Mahenge Gems, which was established in early 2020 and has direct access to miners in the area.
The material began arriving in the Mahenge Gems office around late October/early November, Director Wez Barber said.
At the beginning, they thought it was standard blue spinel because of the large size of the crystals.
The leading source of cobalt-blue spinel is Vietnam’s Luc Yen District, known for its vibrant blue material, though those stones tend to be small.
This Tanzanian material, Barber said, is the “best of both worlds”—good quality, clean, saturated stones that are more than 1.5 carats in size, including some as big as 40 carats.
The colors so far have ranged from a denim blue to a vibrant electric blue, Barber noted.
“We bought as much of it as we could lay our hands on, and still are, because it was such nice material,” he said.
The company sent stones to a few different labs to have it confirmed as cobalt-blue spinel.
Related stories will be right here …
The newly discovered deposit is about 12.5 miles southeast of Mahenge.
The spinel started appearing on the market late last year, according to wholesaler Mahenge Gems, which was established in early 2020 and has direct access to miners in the area.
The material began arriving in the Mahenge Gems office around late October/early November, Director Wez Barber said.
At the beginning, they thought it was standard blue spinel because of the large size of the crystals.
The leading source of cobalt-blue spinel is Vietnam’s Luc Yen District, known for its vibrant blue material, though those stones tend to be small.
This Tanzanian material, Barber said, is the “best of both worlds”—good quality, clean, saturated stones that are more than 1.5 carats in size, including some as big as 40 carats.
The colors so far have ranged from a denim blue to a vibrant electric blue, Barber noted.
“We bought as much of it as we could lay our hands on, and still are, because it was such nice material,” he said.
The company sent stones to a few different labs to have it confirmed as cobalt-blue spinel.
Swiss gem lab SSEF analyzed a selection of the material, confirming cobalt as the main coloring element, in combination with iron.
This makes the Mahenge material similar to cobalt spinel from sources in Sri Lanka, Pakistan, and Vietnam, the lab said.
The Tanzanian material contains characteristic inclusions, SSEF noted, like oriented geometric lamellae with interference colors together with lines of fine particles. It said similar inclusions have been found in red spinel from Morogoro in eastern Tanzania.
Through Raman spectroscopy, SSEF also found colorless apatite and clusters of small zircon inclusions.
Because the deposit was discovered fairly recently, it remains to be seen how much material it will produce.
Barber said that in the past six weeks to two months, very little material has been coming through their office, but he also noted there had been little mining activity due to the rainy season and Ramadan.
With Ramadan ending in early May and the rainy season coming to a close, they should soon be able to ascertain how much more material the deposit might produce.
Those interested in the cobalt-blue spinel can contact Mahenge Gems via its website or follow the company on Instagram.
Mahenge Gems will also have the Tanzanian cobalt-blue spinel on display during the upcoming Las Vegas Market Week. Visit them in the Gems pavilion at JCK Las Vegas at Booth 33105.
Editors' Picks
Sponsored by
More on Sourcing
The Latest
EditorsFeb 03, 2025
Best Jewelry Moments From the 2025 Grammy Awards From Lady Gaga’s 1930s Tiffany & Co. necklace to Taylor Swift’s “T,” Michelle Graff recaps the night’s most memorable jewelry looks.
MajorsFeb 03, 2025
Qurate to Close HSN’s Florida HQ Amid RestructuringLayoffs will reportedly start next month as HSN plans to move into QVC’s location in Pennsylvania.
EditorsFeb 03, 2025
Q&A: 5 Jewelry Designers on Shopping the 2025 Tucson Gem ShowsA group of creatives talked to Associate Editor Lauren McLemore about their approach to the annual Tucson gem, mineral, and fossil shows.
Brought to you by
3 Ways to Capitalize on America’s Newfound Love of Colored GemsColored stones are stepping into a jewelry spotlight typically reserved for diamonds—are you ready to sell color?
AuctionsJan 31, 2025
Elizabeth Taylor’s Diamond Bracelet Outshines Estimate at U.K. AuctionThe auction also featured the sale of a Cartier necklace made when Egyptomania was sweeping Great Britain.
Weekly QuizJan 30, 2025
This Week’s QuizTest your jewelry news knowledge by answering these questions.
CollectionsJan 31, 2025
Piece of the Week: Lalaounis’ Good Luck Charm for 2025The “Blossom Rosette” blooms with love, beauty, and hope for the year ahead.
IndependentsJan 31, 2025
Harvey Rovinsky, Longtime Owner of Bernie Robbins Jewelers, Dies at 77Rovinsky is remembered as a great mentor who made the employees of his stores feel like family.
Brought to you by
3 New Year’s Resolutions for Jewelry Lovers The new year feels like a clean slate, inspiring reflection, hope, and the motivation to become better versions of ourselves.
Events & AwardsJan 31, 2025
Facets of Fire Has a Diamond Challenge for RetailersFor every jeweler who tries their luck, the company will make a donation to Jewelers for Children.
MajorsJan 30, 2025
WJA Chapter Leaders Resign as Fallout From DEI Remarks SnowballsThe boards of at least five chapters have resigned in response to controversial statements the WJA national board president made last month.
Policies & IssuesJan 30, 2025
RJC Executive Director Melanie Grant Is Stepping Down An experienced jewelry writer and curator, Grant led the organization for two years.
CollectionsJan 30, 2025
Pharrell Williams Brings Tahitian Pearls to His New Tiffany & Co. CollectionFive new designs were added, all donning Tahitian cultured pearls and spear-like trident motifs, along with the new “Titan” setting.
Events & AwardsJan 30, 2025
Registration Open for Converge 2025The inaugural event is being co-hosted by the American Gem Society and the Gemological Institute of America.
MajorsJan 30, 2025
24 Karat Club of New York Elects 5 New MembersJewelers of America’s Annie Doresca and AGTA CEO John W. Ford Sr. are among the new members.
CollectionsJan 29, 2025
Boucheron’s High Jewelry Takes the Form of ‘Untamed Nature’The jeweler’s latest high jewelry collection looks into the Boucheron archives to create a “living encyclopedia of high jewelry.”
FinancialsJan 29, 2025
LVMH Watch, Jewelry Sales End the Year DownWatch and jewelry sales slipped 3 percent in 2024, though the luxury conglomerate did see business pick up in the fourth quarter.
MajorsJan 29, 2025
Chanel Names New General Manager of Watches, Fine Jewelry for USOlivier Kessler-Gay will take over the role on March 3.
SurveysJan 29, 2025
Consumer Confidence Slips for Second Consecutive Month It hit a four-month low in January due to concerns about the job market, though consumers remain bullish about the stock market.
Events & AwardsJan 29, 2025
Chris Ploof To Teach Mokume Gane at AJSThe jewelry designer and master metalsmith will present on the ancient Japanese metalworking technique at the Atlanta Jewelry Show in March.
CollectionsJan 28, 2025
Bliss Lau Celebrates the Intricate Mosaic of Identity in New CollectionThe versatile “As We Are” collection features 14 pieces with interlocking designs allowing for 27 different looks worn around the body.
Events & AwardsJan 28, 2025
NouvelleBox Show Returns to New York CityThe showcase, in its second year, will feature more than 20 international brands at its curated event from Feb. 2-4.
Recorded WebinarsJan 28, 2025
Watch: Fine Jewelry Market Predictions for 2025 “My Next Question” guests Sherry Smith and Edahn Golan share their 2025 forecasts, from sales and marketing to what retailers should stock.
Events & AwardsJan 28, 2025
Here Is the 2025 AGTA GemFair Tucson Educational LineupThe seminar series covers topics from market trends and colored stone terminology to working with museums and growing an Instagram profile.
MajorsJan 27, 2025
Le Vian Corp. Chairman Larry LeVian, a Man of Faith and Family, Dies at 73 LeVian is remembered for his leadership in the jewelry industry and for being a selfless and compassionate person.
CrimeJan 27, 2025
New Jersey Jeweler Sentenced to 2 1/2 Years for Evading CustomsMonishkumar Kirankumar Doshi Shah pleaded guilty to evading customs on more than $13.5 million of jewelry imported into the U.S.
SourcingJan 27, 2025
Dev Shetty To Head New Auction House for Rare Colored GemsJemora Gemhouse’s inaugural auction, slated for March, will take place in Dubai and feature polished sapphires.
CollectionsJan 27, 2025
Rachel Quinn Embodies Feelings of Falling in Love in New CollectionQuinn partnered with Gemfields to create “Crazy Love,” which features Zambian emeralds and Mozambican rubies across 10 pieces.
