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.
Oppenheimer Blue
The diamond was named for its previous owner Philip Oppenheimer. It is cut into a rectangle (emerald cut). The Oppenheimer Blue is the largest fancy vivid blue diamond classified by the Gemological Institute of America ever sold at auction; it sold at Christie's in Geneva in May 2016 for US$50.6 million (GBP 34.7m; 56.83m SFr). Two telephone bidders had competed for the diamond; the identity of the purchaser is not publicly known.