"The Rock", the biggest white diamond ever to be sold at a auction is pictured prior to the start of Christie's Magnificent Jewels sales in Geneva on May 11, 2022. - "The Rock", the biggest white diamond ever to be sold at auction, is going under the hammer in Geneva and could fetch up to $30 million -- or more. The 228.31-carat stone, larger than a golf ball, is "a truly exceptional pear-shaped diamond", said Max Fawcett, head of the jewels department at Christie's auction house in Geneva. (Photo by Fabrice COFFRINI / AFP)