Cullinan Diamond
The Cullinan diamond was found below the surface at Premier Mine in Cullinan, Transvaal Colony, by Frederick Wells, surface manager at the mine, on 26 January 1905. It was approximately long, wide, deep, and weighed . Newspapers called it the "Cullinan Diamond", a reference to Sir Thomas Cullinan, who opened the mine in 1902. It was three times the size of the Excelsior Diamond, found in 1893 at Jagersfontein Mine, weighing . Four of its eight surfaces were smooth, indicating that it once had been part of a much larger stone broken up by natural forces. It had a blue-white hue and contained a small pocket of air, which at certain angles produced a rainbow, or Newton's rings.
Marange diamond fields
The Marange diamond fields are an area of widespread small-scale diamond production in Chiadzwa, Mutare West, Zimbabwe. 'Although estimates of the reserves contained in this area vary wildly, some have suggested that it could be home to one of the world's richest diamond deposits'. The hugely prolific fields are regarded by some experts as the world's biggest diamond (in carats, not by value) find in more than a century. Production from Marange is controversial due to ongoing legal wrangles and government crackdowns on illegal miners and allegations of forced labour. In terms of carats produced, the Marange field is the largest diamond producing project in the world, estimated to have produced 16.9 million carats in 2013, or 13% of global rough diamond supply. Marange is estimated to have produced 12.0 million carats in 2012, 8.7 million carats in 2011, and 8.2 million carats in 2010. While some diamond mines produce rough valued at over $1000 per carat, average production at Marange is estimated at under $50 per carat.