On this day in history: Cullinan Diamond discovered, 1905

On 26th January 1905, Frederick Wells noticed something catching the light of the setting sun while making a routine inspection of the Premier Mine in the Transvaal Colony, South Africa where he worked as a superintendent. He climbed up the side of the mineshaft and removed what appeared to be a diamond crystal of such a size that he initially suspected that it was piece of glass. It turned out to be the largest gem-quality diamond ever discovered.

The 3,106.75 carat crystal weighed just over 621 grammes (roughly 1.4 pounds). It became known as the Cullinan Diamond, after the owner of the mine, Sir Thomas Cullinan, who sold it to the Transvaal Government. They presented it to the British King, Edward VII, to mark his 66th birthday on 9th November 1907.

In order that the diamond be transported safely from South Africa to Britain, a team of British detectives travelled on the steamer that - rumour had it - would carry the stone. The 'diamond' on the ship was actually a fake. The real diamond was sent to London by parcel post in a plain package.

Asscher Brothers of Amsterdam received the contract to finish the rough diamond. Joseph Asscher's first attempt to cleave the crystal failed when the steel blade broke leaving the stone undamaged. He succeeded on his second attempt cutting the diamond into two pieces as planned.

The nine largest pieces of the Cullinan Diamond

In all Asscher cut nine major gems and 96 smaller brilliants from the Cullinan Diamond. The largest of these became part of the British Crown Jewels: Cullinan I (530.2 carats), or the Great Star of Africa, is mounted on the Sceptre with the Cross; Cullinan II (317.4 carats), known as the Lesser Star of Africa, is part of the Imperial State Crown; Cullinan III (94.40 carats) is in the finial of Queen Mary's Crown. The other major gems became dress jewellery worn by members of the Royal Family.