‘Rarest of the Rare’ Blue Diamond Expected to Top $48M at Auction
The 15.10-carat fancy vivid blue, mined by Petra last spring and purchased by De Beers and Diacore, heads to Sotheby’s in April.

Sotheby’s announced Wednesday it will offer the 15-carat fancy vivid “De Beers Cullinan Blue Diamond” in a single-lot sale this spring.
The diamond is estimated to sell for more than $48 million, or $3.2 million per carat.
Mining company Petra Diamonds uncovered the original rough, weighing 39.34 carats, at the Cullinan mine in April 2021.
De Beers Group and manufacturer Diacore International, a De Beers sightholder and master diamond cutter, purchased the stone for $40.2 million last July.
Since then, the companies have been analyzing, cutting and polishing the stone to bring the diamond that’s been dubbed the De Beers Cullinan Blue to life.
What emerged is an internally flawless 15.10-carat step-cut fancy vivid blue diamond Sotheby’s is calling the largest vivid blue diamond ever to appear at auction.
The GIA Monograph Report on the stone states: “Achieving a fancy vivid color grade in a step cut or emerald cut adds to the rarity, since most other fancy shapes intensify the body color more efficiently in the face-up position than step cuts. To achieve a fancy vivid grade with a step cut or emerald cut, the inherent bodycolor has to be stronger than virtually every other fancy shape.”
Sotheby’s will offer the diamond in a live single-lot auction in late April—tentatively April 27—anchoring Sotheby’s Hong Kong Luxury Week.
Prior to that, it will be showcased in a worldwide tour, starting in New York before traveling to London, Dubai, Shanghai, Beijing, Shenzhen, and Taipei.
“Blue diamonds of any kind are rare on the market, but this is the rarest of the rare; nothing of remotely similar caliber has appeared at auction in recent years. Hundreds of millions of years in the making, this extraordinary blue diamond is surely one of nature’s finest creations,” said Patti Wong, chairman of Sotheby’s Asia.
“Now brought to dazzling life by the hand of one of the world’s most skillful cutters, it is the ultimate masterpiece—as rare and desirable as the very greatest works of art. At a time of unprecedented demand for the finest, world-class, colored diamonds, we are incredibly excited to bring to the market what is sure to become one of the most celebrated gems in the world.”
According to Sotheby’s, only five blue diamonds weighing more than 10 carats have gone to auction before, with none exceeding 15 carats.
The world auction record for highest price per carat belongs to “The Blue Moon of Josephine,” a 12.03-carat internally flawless cushion-shaped fancy vivid blue diamond, which sold for $48.5 million, or about $4 million per carat, in November 2015.
The “Oppenheimer Blue,” a 14.62-carat fancy vivid blue step-cut diamond, sold for $57.5 million in May 2016, setting the record for the most expensive jewel sold at auction.
The 59.60-carat “Pink Star” diamond later eclipsed the Oppenheimer Blue, selling for $71.2 million in April 2017. It remains the most expensive jewel ever sold at auction.
The Latest

The update came as Anglo took its third write-down on the diamond miner and marketer, which lost more than $500 million in 2025.

Emmanuel Raheb discusses the rise of “GEO” and the importance of having well-written, quality content on your website.

Each received around four years for burglarizing a jewelry store and a coffee shop in Simi Valley, California, last May.

Every jeweler faces the same challenge: helping customers protect what they love. Here’s the solution designed for today’s jewelry business.

Catherine Aulick, a GIA graduate, received the ninth and final Gianmaria Buccellati Foundation Award for Excellence in Jewelry Design.


We asked a jewelry historian, designer, bridal director, and wedding expert what’s trending in engagement rings. Here’s what they said.

Experts from India weigh in the politics, policies, and market dynamics for diamantaires to monitor in 2026 and beyond.

With refreshed branding, a new website, updated courses, and a pathway for growth, DCA is dedicated to supporting retail staff development.

Beth Gerstein discusses the vibe of the new store, what customers want when fine jewelry shopping today, and the details of “Date Night.”

Are arm bands poised to make a comeback? Has red-carpet jewelry become boring? Find out on the second episode of the “My Next Question” podcast.

The Swiss watchmaker is battling declining sales amid a rapid retail expansion, according to a Financial Times report.

The campaign celebrates Giustina Pavanello Rahaminov, the co-founder’s wife and matriarch of the family-owned brand, for her 88th birthday.

Rachel Bennett, a senior jeweler who has been with Borsheims since 2004, earned the award.

After the Supreme Court struck down the IEEPA tariffs, President Trump imposed a 10 percent tax on almost all imports via a different law.

The industry veteran, who was with The Edge Retail Academy for 14 years, joins her husband at the company he founded in 2022.

The vintage signed jewelry retailer chose Miami due to growing client demand in the city and the greater Latin American region.

Former Flight Club executive Jin Lee will bring his experience from the sneaker world to the pre-owned watch marketplace.

Sakamoto, who died in mid-January following a sudden illness, is remembered for his humility and his masterful, architectural designs.

The April event will feature a new VIP shopping day requiring a special ticket.

Bulgari chose the British-Albanian singer-songwriter for her powerful and enduring voice in contemporary culture, the jeweler said.

In a 6-3 ruling, the court said the president exceeded his authority when imposing sweeping tariffs under IEEPA.

Smith encourages salespeople to ask customers questions that elicit the release of oxytocin, the brain’s “feel-good” chemical.

JVC also announced the election of five new board members.

The brooch, our Piece of the Week, shows the chromatic spectrum through a holographic coating on rock crystal.

Raised in an orphanage, Bailey was 18 when she met her husband, Clyde. They opened their North Carolina jewelry store in 1948.

Material Good is celebrating its 10th anniversary as it opens its new store in the Back Bay neighborhood of Boston.

The show will be held March 26-30 at the Miami Beach Convention Center.



























