The Cullinan Diamond is the largest gem-quality rough diamond ever found, weighing 3,106 carats, discovered at the Premier No.2 mine in Cullinan, South Africa, on 26 January 1905. It was named after Thomas Cullinan, the owner of the mine. In April 1905, it was put on sale in London, but despite considerable interest, it was still unsold after two years. In 1907, the Transvaal Colony government bought the Cullinan and Prime Minister Louis Botha presented it to Edward VII, the British king who reigned over the territory, and it was cut by Joseph Asscher & Co. in Amsterdam.
Cullinan produced stones of various cuts and sizes, the largest of which is named Cullinan I, and named the Great Star of Africa by Edward VII, and at 530.4 carats it is the largest clear cut diamond in the world. The stone is mounted in the head of the Sovereign's Sceptre with Cross.
Wikipedia https://en.wikipedia.org/wiki/Cullinan_Diamond
Address (Unnamed Road), Cullinan 1000, South Africa
Coordinates -25°40'15.892" N 28°30'57.049" E