Most expensive diamond rough cut

Petra Diamonds Ltd (UK) sold a 507.9-carat rough diamond - the 19th largest gem ever discovered - for $35.5 million (€25.8 million, £17.2 million) to the Chow Tai Fook Jewelry Co. Ltd (Hong Kong) on 26 February 2010. The stone, named the Petra Heritage, weighed just over 100 g (3.3 oz) and is as big as a chicken's eggs; it was found in September 2009 in South Africa's Cullinan mine. The Cullinan mine, in Pretoria, South Africa, is one of the most lucrative diamond mines - it has here that the 3,106-carat Cullinan Diamond was found; it was later cut to form the 530-carat Great Star of Africa and the 317-carat Lesser Star of Africa set in the British Crown Jewels.