Most expensive diamond ever sold goes for $83.2M

Sotheby's just dropped the hammer on the most expensive diamond ever sold.

The stone, a 59.6-carat flawless pink diamond called the "Pink Star," was auctioned for $83.2 million, according to Sotheby's. That made it the most expensive jewel or diamond ever sold at auction.

The previous record for a diamond sold at auction was $46 million, for a 24.68-carat pink diamond bought by Laurence Graff in 2010.

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The auction follows yesterday's Christie's sale of the largest fancy-vivid orange diamond known to exist, a 14.82-carat stone that sold for $36 million—the highest price-per-carat ever paid at auction.

—By CNBC's Robert Frank. Follow him on Twitter @robtfrank