White diamonds lead Sotheby’s Geneva sale as vivid blue goes unsold

The blue diamond was the headline, but the white stones won the auction. At Sotheby’s High Jewelry sale in Geneva on May 12, a 6.03-carat fancy vivid blue, internally flawless diamond from South Africa’s Cullinan mine failed to find a buyer, while a matched pair of unmounted De Beers white diamonds, each 18.38 carats, became the highest-value lot and sold for about $3.3 million.

That split told the story of the room. The blue stone carried a pre-sale estimate of roughly $9 million to $12 million, or CHF 7.2 million to CHF 9.6 million, and still could not convert its rarity into a bid. Sotheby’s said the stone continued to generate interest after the auction, a reminder that extraordinary color can still draw attention even when it does not clear the floor.

The white diamonds offered something different: certainty. Both were Type IIa, D-color stones, one flawless and the other internally flawless, and each weighed 18.38 carats. As an unmounted pair from De Beers, they were easier to compare, easier to price, and easier to imagine as the center stones in a high-jewelry setting or a modern engagement ring. In a market that often celebrates one-of-a-kind color, the result suggested that collectors still reward top white diamonds for their wearability and their familiar grading language.

The broader sale backed that up. Sotheby’s said the Geneva auction totaled about CHF 23.36 million, or $30.09 million, with 93 percent of the lots sold. More than five paddles were registered for each lot sold on average, the strongest participation Sotheby’s said it had seen in a Geneva jewelry sale in more than five years. More than 60 percent of the pieces sold above their high estimates, a sign that buyers were willing to stretch for material they understood and could benchmark.

Geneva’s auction week also showed that colored diamonds still have an audience when the stone and the story align. Christie’s sold a 5.5-carat blue-green diamond for about $17.3 million, underscoring the continuing pull of rare color. But at Sotheby’s, the clearer message came from the pair of white stones: in a market full of spectacle, classic D-color diamonds still command the deepest confidence.