'Mellon Blue' diamond sells for $25.6 million at Swiss auction Updated 20 mins ago A blue diamond weighing nearly 10 carats has sold at auction in Switzerland for $25.6 million including fees. The “Mellon Blue” is named for the late American arts patron Rachel “Bunny” Mellon. It had been expected to fetch $20-$30 million at the Christie’s auction on Tuesday. The house said the stone came in on the estimated range. The final price includes the “buyer’s premium” and other fees. The auction was the first installment of two days of jewelry auctions in Geneva. On Wednesday, rival Sotheby’s will put up the “Glowing Rose” pink diamond that’s expected to draw bids of around $20 million.

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