The Cullinan diamond is the largest gem diamond crystal ever discovered. In the rough it weighed 3,106 carats, or about one and one half pounds. Because the rough diamond had a cleavage face, many experts believe that the huge stone was only a piece of a much larger diamond which was broken up during weathering.

The Cullian diamond was discovered in Transvaal, South Africa in l095 on an inspection tour of the Premier Mine. It was named after Sir Thomas Cullinan, chair of the mining company.

The South African government bought the rough diamond for $750,000 and presented it to King Edward VII on his birthday in 1907. In 1908, King Edward sent the stone to Amsterdam for cutting.

The Cullian was cut by Joseph Asscher and Company of Amsterdam, who examined the enormous diamond for six months before determining how to cut it. It eventually yielded nine major diamonds and 96 smaller brilliant-cut diamond.

The largest two resulting diamonds were retained for the British Crown Jewels and are the Cullinan I (Great Star of Africa diamond) and the Cullinan II (Lesser Star of Africa diamond).