8) The Wittelsbach-Graff Diamond ($24.3 million)

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Prestigious gemstone Wittelsbach-Graff Diamond has a history which goes as far back as the 17th century. It was part of the Bavarian crown jewelry before disappearing for decades during the 20th century. When it reappeared it was bought by legendry jeweler Laurence Graff for around $24.3 million in an auction.