GENEVA, Nov. 13 -- A blue diamond weighing nearly 10 carats has sold at auction in Switzerland for 20.5 million Swiss francs ($25.6 million) including fees. The pear-shaped 9.51-carat "Mellon Blue" - named for the late American arts patron Rachel "Bunny" Mellon - had been expected to fetch $20-$30 million at the Christie's auction on Tuesday. For decades, the stone was part of Mellon's private collection. The house said the stone came in on the estimated range. The final price includes the "buyer's premium" and other fees. ap...