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.
De Grisogono
In 2017 the company set a new record at Christie's Magnificent Jewels sale in Geneva when it sold the world's biggest-ever emerald cut diamond offered at auction. The 163.41-carat D Flawless stone, which was cut from a 404 carat rough, was incorporated into a necklace designed by Fawaz Gruosi. It fetched 33.5 million Swiss francs, beating the previous record for a D Flawless diamond by nearly five million Swiss francs.