The Rock, the biggest white diamond to ever come up for auction, was sold for $21.9 million on May 11. The auction of the 228.31-carat stone took place at Christie's auction house in Geneva. The Rock is reportedly the size of a golf ball. The Rock, a perfectly symmetrical pear-shaped diamond, was owned by an unnamed owner from North America, reported AFP. This large diamond was extracted from a mine in South Africa in the early 2000s, reported AFP. Watch the video to know more.