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Rare Pink Star diamond 'to set auction record'

25 September 2013 Last updated at 17:28 BST

A flawless 59.6-carat pink diamond is to be auctioned in the Swiss city of Geneva at a record asking price of $60m (£38m).

Sotheby's David Bennett says the diamond belongs in "the ranks of the earth's greatest natural treasures".

Imogen Foulkes took a close look at the diamond.