The Mediterranean Blue Diamond Sold at $21.5 Million
In May 2025, Sotheby’s Geneva became the stage for one of the year’s most important jewelry auctions. Under the spotlight was The Mediterranean Blue, a 10.03-carat Fancy Vivid Blue diamond that drew collectors from across the world. After a tense round of international bidding, the stone achieved $21.5 million, securing its place in the history of exceptional blue diamonds.
The story of the Mediterranean Blue began in South Africa, where it was discovered as a rare rough crystal infused with boron, the element responsible for the blue coloration in diamonds. From there, it underwent a transformation that required exceptional skill. Every decision in the cutting process was calculated — preserving weight while bringing forward the strongest saturation of color. The result was a cushion-modified brilliant cut, measuring 13.07 × 11.79 × 7.18 mm, awarded the coveted grade of Fancy Vivid Blue by the Gemological Institute of America, with clarity graded VS2. Its polish was rated Very Good and its symmetry Good, a balance that allowed brilliance without compromising carat weight.
Blue diamonds of this scale are exceptionally rare. They account for less than 0.02% of all mined diamonds, and among those, very few achieve Fancy Vivid intensity with both clarity and size above 10 carats. This combination of attributes places the Mediterranean Blue in the same league as the Oppenheimer Blue (14.62 carats, $57.5 million) and the Blue Moon of Josephine (12.03 carats, $48.5 million). By comparison, its final result equates to over $2.1 million per carat, a benchmark that reflects both market demand and enduring scarcity.
Ahead of the auction, Sotheby’s presented the stone on a global tour, including exhibitions in Abu Dhabi and Hong Kong, drawing attention from seasoned collectors and new participants eager to witness one of the few blue diamonds of this magnitude to appear at auction. When the gem finally reached Geneva, bidding quickly surpassed its estimate of $19–20 million before closing at $21.5 million. The buyer has chosen to remain anonymous — a reminder of how discretion and exclusivity continue to define acquisitions at this level.
For the high jewelry market, the sale confirmed what history has consistently demonstrated: the very rarest natural colored diamonds continue to command extraordinary results, regardless of wider shifts in the diamond trade. While lab-grown diamonds and changing consumer preferences reshape parts of the industry, gems such as the Mediterranean Blue remain in a class of their own — irreplaceable natural wonders that serve both as cultural symbols and as assets of long-term value.
With its origin, grading, and result, the Mediterranean Blue now joins the shortlist of blue diamonds that define their era. For collectors, it represents more than a jewel; it is a once-in-a-generation opportunity to own a part of nature’s most elusive brilliance.
Photography courtesy of Sotheby’s.
Gem Exploring Editorial.
