On this day in 1905, the world’s largest diamond was found. The diamond was discovered in a premier mine in Pretoria, South Africa. A 3,106-carat diamond was discovered during a routine inspection by the mine’s manager. The diamond weighed 1.33 pounds and it was named the “Cullinan.”

A miner named Frederick Wells was 18 feet below ground when he noticed a sparkle in the dark above him. That afternoon, his discovery was shown to Sir Thomas Cullinan, the owner of the mine. Cullinan sold the diamond to the Transvaal Provincial government, which gave the stone to Britain’s King Edward VII for his birthday.

Worried that the diamond could get stolen from the shipment from Africa to London, Edward arranged to send a fake diamond aboard a steamer ship loaded with detectives. While the decoy diamond slowly made its way from Africa on the ship, the Cullinan was sent to England in a plain box.

Edward entrusted the cutting of the “Cullinan” to Joseph Asscher, the head of the Asscher Diamond Company in Amsterdam. Asscher, who had cut the famous Excelsior Diamond (a 971-carat diamond found in 1893), inspected the diamond for half a year before attempting the cut. On his first attempt, the steel blade broke, with no effect on the diamond. On the second attempt, the diamond shattered.

The “Cullinan” was later cut into 9 large stones and about 100 smaller ones. All of the stones were valued at millions of dollars. The largest stone is called the “Star of Africa I” and at 530 carats, it is the largest-cut, fine-quality, colorless diamond in the world. The second largest stone, the “Star of Africa II,” is 317 carats. Both of these stones are displayed at the Tower of London with Britain’s other quality jewels. The “Star of Africa I” is mounted in the British Sovereign’s Royal Scepter and the “Star of Africa II” is set in the Imperial State Crown.