The Cullinan Diamond, found in South Africa in 1905, is the largest rough gem-quality diamond ever found, at 3,106 carats. Although a carbonado found in Brazil weighed more than 3,600 carats, no gem-quality material was able to be extracted from it, and the Cullinan is still one of the most remarkable stones ever found. It was named after Sir Thomas Cullinan, the owner of the diamond mine.
The stone was cut into three large parts by Asscher Brothers of Amsterdam, and eventually into some 11 large gem-quality stones and a number of smaller fragments. The largest polished gem from the stone is named Cullinan I or the Great Star of Africa, and at 530.2 carats is still the largest polished diamond in the world. It is now mounted in the head of the royal sceptre in the British crown jewels. The second largest gem from the Cullinan stone, Cullinan II or the Lesser Star of Africa, at 317.4 carats, is the second largest polished diamond in the world and is also part of the British crown jewels, as it forms a part of the Imperial State Crown. Both gems are on display at the Tower of London.