Three other special white stones of similar color and clarity to the diamond were also found on the same site. Even though large in their own right - between 53 and 168 carats, they pale in sale the the 507 carat diamond. The stellar gemstone is considered to be amongst the top 20 largest high quality rough diamonds ever found worldwide.
Photo credit Petra Diamonds
The Cullinan mine is no stranger to large diamond. It is well known as the source of the world's largest diamond ever recovered -the "Cullian" which weighs over 3100 carats in its rough form. It was also the birthplace of the Elizabeth Taylor - Richard Bruton Diamond which was 69 carats polished.
Petra is still trying to decide what to do with the mammoth stone. Diamonds of this size are very rare, and the company is looking at various options before committing to any potential sale. Petra would like to ensure a large price tag but also want to make sure that the diamond's legend will also live on.
Since rough diamonds can lose half their carat weigh when the stone is polished, it is hard to say what the final carat weight will be - or indeed whether it will remain as one large stone, or be cut into smaller (but still immense) diamonds.