10.02-carat blue diamond fetches $8.7 million at Sotheby's auction

A 10.02-carat fancy intense blue diamond sold for $8.7 million at Sotheby’s High Jewelry auction in New York, turning a single stone into the spring season’s priciest jewelry lot. The cut-cornered rectangular modified brilliant diamond was listed as Lot 120 and closed at more than $2.7 million above its pre-sale high estimate of $6 million.

The stone carried the kind of paperwork serious collectors love to hear about: GIA report no. 2235885839, dated May 28, 2026, described it as Fancy Intense Blue, Natural color, VS2 clarity, and identified it as Type IIb. Sotheby’s said the buyer also would have the option to use Sotheby’s Bespoke to design a custom jewel around it, which is exactly how a lot like this moves from auction trophy to future heirloom.

That is the romance of rare stones at their most persuasive. A blue diamond of this size does not just signal wealth; it signals certainty, taste, and a kind of devotion that wants to be remembered. JCK noted that it was only the third fancy intense blue diamond of 10 carats or more to come to auction since 2008, which helps explain why these stones feel less like merchandise and more like occasion-defining objects. In Valentine’s terms, the appeal is not subtle. It is the fantasy of giving something so scarce that the gift itself becomes the story.

The rest of the sale reinforced that appetite. Sotheby’s High Jewelry auction totaled $43.4 million, with 98% of its 119 lots sold and more than 63% of them finishing above their high estimates. Strong results also came from a 5.02-carat fancy intense pink diamond ring that sold for $2.9 million and a 7.70-carat Brazilian Paraíba tourmaline that brought $1.4 million, alongside jewelry by Van Cleef & Arpels, Graff, and Cartier. For anyone shopping with a Valentine’s budget that lives far below $8.7 million, the lesson is plain: the market keeps rewarding blue, pink, and vividly colored stones that read as personal, rare, and just a little bit unforgettable.