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.
DeYoung Red Diamond
The DeYoung Red Diamond is a 5.03-carat unmounted rare red diamond. It is the third-largest red diamond in the world, and the only one on public display. Sydney DeYoung (for whom the diamond is named) obtained the diamond, which was mistaken for a garnet, at a flea market. The diamond was given to the Smithsonian Institution after DeYoung's death in 1986.