Sotheby's New York sale spotlights 10.02-carat blue diamond, Harry Winston necklace

Sotheby’s New York High Jewelry sale will be led by a 10.02-carat unmounted fancy intense blue diamond estimated at more than $6 million, a lot that shows where the top end of the market still places its bets: on rare natural color, clean presentation and stones that are hard to explain away as anything but extraordinary. The sale also brings a circa-1960s Harry Winston necklace-bracelet combination to the block, a signed jewel with more than 120 carats of diamonds and the sort of period craftsmanship that collectors continue to reward.

The blue diamond is cataloged as a Magnificent Unmounted Fancy Intense Blue Diamond, and its rarity is central to the pitch. Sotheby’s says the Gemological Institute of America estimates that only 0.3% of colored diamonds submitted to its lab are predominantly blue, and Fancy Intense stones with unmodified color are scarcer still. The house also points to research suggesting blue diamonds form 400 to 600 kilometers below the earth’s surface, a reminder that the most prized colored diamonds are valued as much for the geology that made them as for their beauty.

Public viewing will run June 11 to 15 at 945 Madison Avenue in New York, before the sale on June 16. Sotheby’s has renamed its Magnificent Jewels auctions as High Jewelry, a subtle but telling shift that frames the category less as a commodity sale and more as a market for rare stones, signed houses and superb manufacture.

The Harry Winston lot, cataloged as an Exceptional Diamond Necklace-Bracelet Combination, gives the other half of the sale its historical weight. The piece is detachable into four sections and can be worn as two bracelets or as a necklace of varying lengths, a flexibility that adds practical value to its more than 120 carats of diamonds. Its estimate is $800,000 to $1.2 million, and its design is unusual for Harry Winston: the house’s Winston Cluster typically favors marquise and pear shapes, while this example prominently uses round diamonds.

That combination of rarity and name recognition is exactly what the market has been rewarding. Sotheby’s sold The Mediterranean Blue, a 10.03-carat fancy vivid blue diamond, for $21.5 million at its Geneva High Jewelry sale in May 2025, a result that underscored how fiercely collectors will compete for top-tier blue diamonds. Against that backdrop, the New York blue stone and the signed Winston jewel suggest the same message: at the highest level, buyers still pay up for stones with exceptional color, documented pedigree and a story that can survive scrutiny.