The largest diamond discovered in more than a century went on display in London on Tuesday ahead of a record-breaking US$70 million ($100m) sale.
Lesedi la Rona, which is three billion years old, is a staggering 1,109 carats and the size of a tennis ball.
It was uncovered in Botswana last year and has been described as a "once in a lifetime discovery".
The gem, which is only beaten in size by the diamond now found in the Crown Jewels, was on display at Sotheby's Bond Street headquarters in London.
Sotheby's will sell Lesedi la Rona on June 29, with the auction house expecting it to sell for a world record US$70 million.
The gem was uncovered by Lucara Diamond Corp at its Karowe mine in Botswana in November.
Nothing of the size and quality of the Lesedi la Rona, which translates as 'our light' in the Tswana language, has been been found in more than 100 years.
In terms of its size, the 'rough' is exceeded only by the 3016.75-carat Cullinan Diamond, which was mined in South Africa in 1905.
The Cullinan ended up producing nine diamonds which are now found in the Crown Jewels.
Independent reports say the Lesedi la Rona has the potential to yield the largest top-quality diamond that has ever been cut and polished.
The record is currently held by the pear-shaped Great Star of Africa, which came from the Cullinan and weighs 530.20 carats.