A South African mining company claimed to have discovered the world’s largest diamond, which is double the size of the current biggest known stone, the Cullinan.

Brett Jolly, a spokesman for the company, Two Point Five Construction, said the rough diamond - reportedly a 7,000-carat stone about the size of a coconut - had been transported under tight security to Johannesburg and deposited in a bank vault.

Brett Jolly, a representative at Two Point Five Construction Company, said the rough diamond, which weighs 7,000 carat had been shipped to Johannesburg under tight protection and posited in the vault.

In a local radio interview, Brett stated that he was consulting with attorneys about future steps regarding the diamond.

The Cullinan that was discovered in South Africa over 100 years ago turned part of Britain’s Crown Gems.

Before anything else occurs, the stone will have to be analyzed by the South African Diamond Board that lists all diamonds to verify its genuineness and that it was discovered at a certified diamond mining site.

Tom Tweedy, a speaker for world’s largest diamond company told that if the discovery were real it would be the stone of the century.

“But the pics show it to be light green in color that while possible is very rare. I have my doubts that it is real," Mr Tweedy added.

Several diamond industry representatives said that while the specific place of the discovery had yet to be disclosed, it was standard practice not to do so with a potentially very valuable diamond for security reasons.

Les Milner, a gem scientist with the Jewellery Council Laboratories, the umbrella organisation of South Africa's precious stones trade, said, “If it is what it is, it's very, very rare. I tend to be very sceptical about this kind of thing.”