The Cullinan Diamond, unearthed at the Premier Mine №2 in Cullinan near Pretoria, is still the largest gem-quality diamond ever discovered, weighing 3,106.75 carats (621.35 g).
It was found January 26th, 1905, and in 1907 the Transvaal colony bought the diamond for a £150,000 and presented it to King Edward VII, then reigning King of the United Kingdom.
Joseph Asscher of Amsterdam were entrusted with the task of cutting the diamond.
After a long and daunting process, they produced Cullinan I, also called The Great Star of Africa, which at over 530 carats (160g) is the largest clear-cut diamond in the world. The stone was mounted in the head of the Sovereign’s Scepter with Cross.
The second-largest of the stones, Cullinan II and named the Second Star of Africa, weighing 317.4 carats (63.48g) was mounted in the Imperial State Crown. Both are part of the Crown Jewels.
Seven other major diamonds, weighing a total of 208.3 carats (41.66 g), are privately owned by Queen Elizabeth II, who inherited them from her grandmother, Queen Mary, in 1953.
It is widely believed that the Cullinan diamond was in fact, a portion of a larger stone.