Oppenheimer Diamond

The Oppenheimer Diamond, a nearly perfectly formed 253.7 carat (50.74 g) yellow diamond crystal, is one of the largest uncut diamonds in the world. It measures approximately 20 × 20 millimeters. It was discovered in the Dutoitspan Mine, Kimberley, South Africa, in 1964. Harry Winston acquired the stone and presented it to the Smithsonian Institution in memory of Sir Ernest Oppenheimer.
References