The largest white diamond to ever come up for auction has been sold for $21.9 million, at Christie’s in Geneva.

The 228.31-carat, pear-shaped gemstone — dubbed “The Rock” — originated from South Africa, where some of the largest diamonds in the world have been found, including the pear-shaped “Star of Africa” and rose cushion cut “Golden Jubilee.”

“The Rock” is about the size of a golf ball and was previously worn as a lavish Cartier necklace by its former owner. Along with the pear-shaped stone, the new owner will also receive a round diamond and platinum pendant mounting from the French luxury brand.

The head of Christie’s jewelry department in Geneva explained why “The Rock” is a particularly unique stone.

He said, “Often with these largest stones, they sacrifice some of the shape in order to keep the weight. This is a perfectly symmetrical pear-shape form and… one of the rarest gems ever to be sold at auction.”