The Cullinan Diamond, found at the Premier Mine in Transvall, South Africa, is the world’s largest gem diamond. When first found, its rough form weighed around 3,106 carats.
Named after Sir Thomas Cullinan, the mine’s discoverer, the diamond was presented in 1907 to King Edward VII, the reigning British Monarch.
From the diamond, the Great Star of Africa, weighing 530.2 carats, sits in the British Sovereign’s Sceptre with Cross. The other, the Second Star of Africa, weighs 317 carats and adrons the Imperial State Crown — the largest and most valuable stone in it.
The remaining parts of the diamond, Cullinan III–IX, are all part of the British monarchy’s personal collection.
Britannica Editors. “Cullinan diamond“. Encyclopedia Britannica, 15 Oct. 2025, https://www.britannica.com/topic/Cullinan-Diamond. Accessed 6 November 2025.