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.
Petra Diamonds
Kimberley Underground comprises three kimberlite pipe mines in close proximity: Bultfontein, Dutoitspan and Wesselton. These mines were integral to the economic development of South Africa as their output effectively financed development of the nascent gold industry. They are currently mining at depths of between 845 and 995 metres below surface. The mines have a history of producing large diamonds and fancy yellows, such as the Oppenheimer Diamond (253 carats rough). The largest diamond ever recovered at Kimberley Underground was +800 carats and the mine is also the source of the Kimberley Octahedral, at 616 carats, one of the largest uncut diamonds in the world.