London, Sept 30 : A diamond the size of a chicken egg and worth an estimated 12 million pounds has been found at the Cullinan mine northeast of Pretoria.

One of the world''s biggest-ever sparklers – a 507.55-carat whopper – was showed off by mining group Petra Diamonds’ chief executive Johan Dippenaar.

The Cullinan mine, near Pretoria, is part owned by UK firm Petra.

The original 3,106 carat Cullinan diamond became the largest rough diamond ever discovered when it was found on January 26 1905 by miner Frederick Wells, reports The Sun.

Once polished, the stone was presented to King Edward VII and now forms part of the British crown jewels.

It was only overtaken as the world''s biggest polished diamond in 1985 with the discovery of the Golden Jubilee diamond, also at the Cullinan mine. (ANI)