A Christie's member of staff displays a pear-shaped, D colour, flawless diamond of 101.73 carats during an auction preview in Geneva April 30, 2013. The successful buyer will have the privilege to give the gemstone a name as it is the first time this item is offered on sale. It is expected to sell around CHF 28,000,000 (US$ 30,000,000) when it goes into auction May 15, 2013 in Geneva.DENIS BALIBOUSE/Reuters