A diamond coveted by kings, queens and princes for centuries, used to reinforce alliances between nations and pawned to pay off royal debts sold for $9.57m (Dh35.2m) at Sotheby\'s in Geneva on Tuesday night. The auction house called the \"Beau Sancy\" diamond \"one of the most important historic diamonds ever to come to auction\", reflecting its role in the fluctuating fortunes of Europe\'s royal families for more than 400 years. \"The legendary Beau Sancy is a truly magical stone that has entranced generations of royal owners and continues to exert a powerful influence over all who see it,\" said David Bennett, Sotheby\'s chairman of jewellery in Europe and the Middle East, in a statement. \"Its supreme historical importance was reflected tonight in the strength of the bidding and the remarkable result realised.\"No fewer than five bidders competed for the stone, driving the price to nearly five times above its pre-sale low estimate of 1.85 million Swiss francs in an eight minute battle before it was bought by an anonymous bidder, Sotheby\'s said. The stone, a 35-carat modified \"pear double rose cut\" diamond belonging to Georg Friedrich, Prince of Prussia and head of the former ruling dynasty of the German empire, had been expected to fetch $2 million to $4 million. \"It\'s a stone that appeals to me greatly as a survivor of all those tumultuous events,\" Bennett told Reuters. \"Stones from royal collections hardly ever appear at auction. In my career this is an absolute one-off.\" The diamond originated from the mines in India near Golconda and was acquired by Nicolas de Harlay, Lord of Sancy, in Constantinople in the 1500s.