507 carat white diamond discovered in SA's Cullinan mine

 
Mining group Petra Diamonds has discovered a 507.55 carat white diamond at South Africa’s Cullinan mine, one of the largest high-quality rough diamonds ever found, the firm said on Tuesday.
“This spectacular gemstone was recovered on Thursday and is currently with experts for analysis,” said a statement released by the London-listed company which operates mainly in Africa.
Initial examinations of the diamond which weighs just over 100 grams (3.5 ounces), have shown it to be of exceptional colour and clarity.
The diamond is undergoing colour grading, but is believed to be a rare Type II diamond, with very low traces of nitrogen -- considered an impurity - making them among the most transparent and colourless of the gems.
“The Cullinan mine has again given the world a spectacularly beautiful and important diamond... we now eagerly await the findings of the expert analysis,” said Johan Dippenaar, Petra’s chief executive.