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.
Yair Shimansky
The Brilliant 10 diamond design is a 71 facet round brilliant cut diamond design developed and patented by Shimansky. It's been stated as being the most brilliant diamond in the world. The diamond is currently the only diamond that has no light leakage, in which all of the light that enters through the table and the crown is reflected back. In contrast, a regular round brilliant diamond with 57 facets loses around 8%-12% of light even if cut to ideal proportions, in which the light loss is around the girdle area of the diamond.