‘Mediterranean Blue’ Diamond Sells for $21.5 Million at Sotheby’s Geneva

A rare blue diamond known as the Mediterranean Blue took center stage at Sotheby’s recent high jewelry auction in Geneva, selling for CHF 17.9 million (around $21.5 million). 

Weighing 10.03 carats, the fancy vivid blue diamond achieved approximately $2.1 million per carat, making it the most valuable jewel sold at auction so far this year.

The diamond, which features a cushion modified brilliant cut and VS2 clarity, was purchased by an American private collector after a competitive three-minute bidding exchange between two determined buyers. According to Sotheby’s, interest in the stone was high in the lead-up to the sale.

The diamond was cut from a 31.94-carat rough discovered in 2023 at the Cullinan mine in South Africa, operated by Petra Diamonds. Its final price came in line with Sotheby’s guidance of “around $20 million,” although some dealers believed the stone had potential to reach closer to $30 million.

Expectations around the sale were heightened after Christie’s withdrew a major competing lot—the Golconda Blue, a 23.24-carat fancy vivid blue diamond expected to fetch up to $50 million—from its own Geneva auction scheduled for the following day.

While the Mediterranean Blue generated strong interest, some in the industry suggested that broader geopolitical and economic concerns, including ongoing US-China trade tensions, may have tempered aggressive bidding.

Sotheby’s total sales for the evening reached CHF 42.1 million (approximately $50.2 million), reinforcing Geneva’s reputation as a key global hub for high-value jewelry auctions.