‘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 company plans to raise the prices of select watches to offset the impact of tariffs.

Between tariffs and the sky-high cost of gold, designers enter this year’s Las Vegas shows with a lot of questions and few answers.

Designed by founder Renato and his daughter Serena Cipullo, it showcases a flame motif representing unity and the power of gathering.

More shoppers are walking out without buying. Here’s how smart jewelers can bring them back—and the tool they need to do it right.

However, the tariffs remain in effect in the short term, as an appeals court has stayed the U.S. Court of International Trade’s decision.


The pop icon is one step closer to launching her “B Tiny” jewelry collection, a collection she first began posting about last fall.

Sponsored by Stuller

Gain access to the most exclusive and coveted antique pieces from trusted dealers during Las Vegas Jewelry Week.

It was featured in the miner’s latest sale, which brought in $24.8 million.

GemText AI uses artificial intelligence to generate tailored product titles, descriptions, and tags with jewelry-specific language.

The 3,300-square foot location is the jeweler's largest store in North America.

Aging and with myriad health issues, none will serve time for their roles in robbing the billionaire celebrity at gunpoint in 2016.

The WNBA team received rings imbued with meaning, from leaf motifs and its Liberty torch to the number of diamonds used.

A longtime executive at RDI Diamonds, Rickard has served on the JBT board for the past five years.

The two organizations have signed an affiliation agreement that’s expected to be finalized in the coming weeks.

Get a taste of the delicious candy-like gemstones in this Amanda’s Style File.

JSA’s Scott Guginsky provided a list of nine security measures jewelers should observe while locking up for the long weekend.

From Lau’s “Love of a Kind” series, the engagement ring was inspired by the moon and holds a different meaning depending on how it is worn.

The lab has adjusted the scale it uses for nacre grading.

Sponsored by GCAL by Sarine

David Walton will serve three years’ probation after an incident in a hotel bar led to the death of West Virginia jeweler David Ettinger.

The retailer also provided an update on how the tariffs situation in the U.S. is affecting its business.

The family-owned jeweler in Great Falls, Virginia, will be celebrating its golden jubilee with a year’s worth of events.

The nonprofit elected five judges who will decide the winners of its design competition.

This year’s edition includes articles on the favorite tools of notable designers, evaluating when to outsource production, and more.

The jeweler’s high jewelry collection features extraordinary gemstones, like a 241.06-carat emerald and the world’s fourth-largest spinel.

In a special column for the State of the Majors, Edahn Golan breaks down what the top-performing fine jewelry sellers are doing right.