A Christie’s employee presents an unmounted heart-shaped diamond, type IIa diamond, weighing 56.15 carats, with exellent polish and symmetry,¬† during a press preview in Geneva, Switzerland, on Friday, April 01, 2011. The gemstone is estimated to fetch 9’000’000 – 12’000’000 Swiss Francs at the Christie’s jewels sale on may 18, 2011 in Geneva. (KEYSTONE/Christian Brun)

A Christie’s member of staff displays an unmounted heart-shaped D colour, Type IIa diamond weighing 56.15 carats during an auction preview in Geneva April 1, 2011. The item is expected to sell between CHF 9,000,000 and 12,000,000 (US$ 9,000,000 and 12,000,000) when it goes into auction May 18, 2011 in Geneva. REUTERS/Denis Balibouse