The Cullinan, 3,106.75 carats (about 1.4 pounds), is the largest rough gem-quality diamond ever discovered. The Cullinan was found by miner Thomas Evan Powell on January 26, 1905 in a mine in South Africa and was named after Sir Thomas Cullinan, the owner of the mine.
The massive diamond was bought by the South African government and presented to British King Edward VII on his birthday; however, a security problem was posed when the Cullinan was to be transported from South Africa to England. Detectives from London were placed on a steamboat headed for Europe with a fake stone, which was rumored to be the Cullinan. This was a divisionary tactic, intended to attract thieves who might be interested in stealing the massive diamond. The actual Cullinan diamond was safely shipped to England in the standard mailing system via parcel post.
The Cullinan has since been cut into nine smaller stones, with the biggest of them known as the Great Star of Africa.
Also take a look at some other Famous Diamonds:
The Hope Diamond
The Centenary Diamond
The Regent Diamond
The Koh-I-Nur Diamond
The Orlov Diamond