Colored diamonds, especially blue ones, are gaining in importance—they are now perceived not only as beautiful but also as an excellent investment. The "Mediterranean Blue" auction is further proof that rare stones can attract record sums and generate enormous interest. Such a stone is an excellent investment as well as a beautiful adornment for a dream engagement ring.
In May of this year, Sotheby's auctioned a unique 10.03-carat Mediterranean Blue diamond in Geneva. This blue diamond attracted the attention of both collectors and investors from around the world. The stone sold for $21.5 million, or approximately 17.9 million Swiss francs—slightly above its estimated value of $20 million. This was one of the highest prices achieved for a diamond in 2025.
The diamond is classified as a Fancy Vivid Blue, Type IIb, with a clarity of VS2. It comes from the legendary Cullinan mine in South Africa and was cut from a 31.94-carat rough. The analysis and polishing process took over a year and a half. During the auction, the Mediterranean Blue became the focal point of the sale—bidding lasted three minutes, and the stone ended up in the hands of an American collector.
This stone is worth noting for several reasons. Firstly, its exceptional rarity and uniqueness—fewer than 0.1% of diamonds have any blue hue, and the Fancy Vivid Blue grade is among the rarest. Secondly, we are observing a clear investment trend—the rising prices of colored diamonds indicate that they are being perceived as an attractive alternative to traditional investment assets. And finally, the scale and prestige of the transaction itself—the sale of the Mediterranean Blue was one of the largest not only in 2025 but also in Sotheby's auction history, earning it the title of the best-selling gemstone of the season.
Source: https://www.sothebys.com/en/buy/auction/2025/high-jewellery-ge2502/the-mediterranean-blue
https://www.jckonline.com/editorial-article/rare-10-ct-blue-21-5-million
https://phys.org/news/2025-05-rare-blue-diamond-mn-auction.html
https://www.forbes.com/sites/anthonydemarco/2025/05/13/the-103-carat-mediterranean-blue-diamond-fetches-215-million
