London: The largest uncut diamond to be discovered in a century and aged 2 to 3 billion years old is expected to fetch nearly $100 million when it is put up for auction at Sotheby's next week.

The "Lesedi La Rona" meaning "our light" in Tswana, the language of Botswana where the stone was mined last year, weighs 1109 carats and is the size of a small ball.

It is the largest rough diamond find since the discovery of the Cullinan Diamond in 1905, which weighed 3106.75 carats and yielded nine polished gems, including the Great Star of Africa which is set into Queen Elizabeth II's sceptre.

Conservative predictions put Lesedi La Rona's biggest gem at 400 carats, but some analysts believe it could hold a stone greater than 500 carats and potentially rival the Great Star of Africa to be the largest single diamond in the world.