Pretoria - A rare 507 carat white diamond was discovered at the Cullinan Mine near Pretoria.
"This spectacular gemstone was recovered on Thursday, 24 September, and is currently with experts for analysis," said a statement released by Mining group Petra Diamonds, on Tuesday.
According to the London-listed company which operates mainly in Africa, initial examinations indicate that it is of exceptional colour and clarity, and most likely to be a Type I diamond.
The precious stone was found alongside three other special white gems of similar colour and clarity, a large diamond of 168 carats and two other stones of 58.50 and 53.30 carats.
At 507 carats (just over 100 grams) the diamond is considered to be among the top 20 largest high quality rough diamonds ever found worldwide.
"The Cullinan mine has again given the world a spectacularly beautiful and important diamond," said Petra's chief executive Johan Dippenaar.
"Initial indications are that it is of exceptional colour and clarity, which suggest extraordinary potential for its polished yield."
The mine, which was previously owned by diamond mining giant De Beers, is renowned for the discovery of the famed Cullinan Diamond in 1905, which is part of the British crown jewels weighing 3 106 carats.
In May 2008, the mine produced a sparkling 101.27 carat diamond, roughly the size of a ping-pong ball.
The Cullinan Diamond Mine is the third richest diamond producing mine in South Africa.