A diamond the size of a chicken egg has been unearthed in South Africa.

The more-than-100-gram gem was discovered last week at the Cullinan mine northeast of Pretoria.

Though not yet assigned a value, the diamond is described as having exceptional color and clarity.

It's estimated to be among the world's top twenty high-quality gems. The mine also produced the largest diamond ever found -- the Cullinan which was 3,106 carats before being cut.