A Christie's employee poses with the 14.62 carats Oppenheimer Blue diamond during a preview in Geneva, Switzerland May 12, 2016. The large and rare diamond, sold for 56.837 million Swiss francs ($57.6 million) at auction on May 18, setting a world record for any gem after a dramatic see-saw bidding process, Christie's in Geneva said. [Photo/Xinhua/Agencies]