The largest white diamond ever auctioned has yielded less than expected. Nevertheless, the stone went under the hammer in Geneva for 18.8 million dollars.

The value of the so-called The Rock was estimated by auction house Christie’s at 20 to 30 million dollars.

The rare 228.31-carat gemstone, larger than a golf ball, was mined and polished in South Africa over twenty years ago. The Rock was recently unveiled at Christie’s Dubai before going on tour.

Five years ago, a smaller white diamond of 163.41 carats was sold in Geneva for the world record of $33.7 million.