On this day in 1905, the legendary Cullinan diamond was discovered at the Premier Mine in Pretoria, South Africa. At over 3,100 carats and weighing 1 1/3 pounds, it was the largest rough gem-quality diamond ever found.
The diamond takes its name from the mine’s owner, Sir Thomas Cullinan, who sold the diamond to the South African Transvaal government. When the provincial rulers decided to present the gem to Britain’s king Edward VII as a birthday gift, the king feared the danger the high-profile jewel would attract on its transcontinental trip. So, a decoy was shipped on a steamer full of detectives, and the real stone was sent to London in a plain package – registered mail, of course!
The famous diamond cleaver Joseph Asscher of Amsterdam was entrusted with the cutting. He studied the diamond for six months learning its structure and observing the irregularity at its center, a black spot caused by internal strain. There is an urban legend that the steel blade broke with the first strike, and that when Asscher successfully split the diamond on the second try, he fainted.
The Cullinan was eventually split into nine large pieces and about 100 smaller ones of various cuts. The three largest are on display in the Tower of London with the Royal Crown Jewels. The biggest, Cullinan I (also called the Star of Africa, pictured above) weighs 500 carats and is the largest cut colorless fine diamond in the world; it is mounted in the British Royal Scepter. At 317 carats, “Cullinan II” is mounted in the Imperial State Crown.