10 Ct. Blue Diamond Reaches $8.7M in Sotheby’s Sale

By Annie Davidson Watson | June 17, 2026

An unmounted 10.02 ct. fancy intense blue diamond achieved $8.7 million at Sotheby’s in New York’s High Jewelry sale on June 16. The cut-cornered rectangular modified brilliant stone is only the third fancy intense blue diamond of 10 cts. or more to come to auction since 2008.

Other lots feature rings set with high-carat colored diamonds. They include a 13.77 ct. fancy light purplish-pink diamond that is cut-cornered and rectangular-shape (sold for $1.5 million); a 6.76 ct. fancy grayish-blue cushion-cut stone, surrounded by pink diamonds and flanked by shield-cut diamonds (sold for $1.2 million); a 5.02 ct. oval fancy intense pink, with two light pink side stones of 0.4+ ct. each (sold for $2.9 million); and a 4.19 ct. fancy purple-pink oval, with round diamonds accenting the band (estimated to reach $1 million to $1.5 million).

sothebys pink diamond — *Ring with 5.02 ct. fancy intense pink diamond and 0.42 and 0.44 ct. light pink diamonds, which sold for $2.9 million*

The cover lot was a 1960s Harry Winston diamond necklace, an unusually round-diamond-forward composition for a house whose signature designs typically lean toward marquise and pear shapes. The piece boasts more than 120 cts., in trefoil clusters of marquise diamonds between round stone pairings and can be converted for wear as two bracelets. The necklace achieved $998,400.

harry winston necklace — *Harry Winston necklace, convertible to bracelets, with over 120 cts. t.w. diamonds, sold for $998,400.*

Continuing Sotheby’s collaboration with De Beers, the June 16 sale offered an 11.33 ct. internally flawless old mine-cut diamond (D color, type IIa), which sold for $896,000, as well as two rings with 2.01 ct. pear-shape diamonds, which sold for $23,040 and $21,760, respectively. A portion of proceeds from the rings will go to the Peace Parks Foundation, a conservation charity cofounded by the late Nelson Mandela.

rene necklace — *René Lalique necklace—convertible to bracelets in silver-topped gold with diamonds—from the Morgan family, sold for $48,640.*

Other highlights in the Sotheby’s event include five Brazilian Paraiba tourmalines, 6.11 to 8.48 ct., that together achieved $3.4 million. They come from a private collection assembled by the heir to an American media dynasty (who discovered the stones through a jeweler he met while fundraising for the Juvenile Diabetes Research Foundation). The stones are being sold individually except for a pair going as one lot.

The most valuable of the Paraiba offerings was a 7.7 ct. oval-shape tourmaline estimated at $350,000–550,000 that ultimately achieved an exceptional $1.4 million after a three-minute bidding battle between two parties.

Among antique pieces with noteworthy provenance, the auction includes a Lalique diamond necklace dating to the 1890s, owned by descendants of Elizabeth Sarah Morgan Jay, who was believed to received it as a wedding gift from her relative J.P. Morgan in 1910. The necklace—convertible to bracelets in silver-topped gold with diamonds—sold for $48,640.

This is an updated version of an article that first published on JCKonline.com on June 15, 2026.

(Photos courtesy of Sotheby’s)

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