Petra unveils largest-ever blue diamond found at Cullinan mine

The London-listed company said further tests were needed on the “exceptional” stone before it could determine the value of the gem, the largest ever found in the mine since Petra acquired it in 2008.

It added it would not look to sell the stone before the end of its current financial year on June 30.

CEO Johan Dippenaar holding the exceptional 122.52 carat blue diamond recovered in June 2014.

“So far, the highest price on record paid for a rough diamond was $35.3m, paid in February 2010 for a 507 carat white stone, also recovered from Cullinan. We think that this stone may break that record,” finnCap analyst Martin Potts told BBC News.

In February, the same firm sold a 29.6-carat blue diamond for $25.6m and a 25.5-carat one for $16.9m last year.

The Cullinan mine, located at the foothills of the Magaliesberg mountain range, is renowned for producing large blue diamonds and is the site of the discovery of the world’s largest gem 109 years ago.

“The rarity of a blue diamond of this magnitude sets it apart as a truly significant find,” Petra said.

The world’s biggest certified diamond is the 3,106-carat Cullinan, found at the mine near Pretoria in 1905. It was cut to form the Great Star of Africa and the Lesser Star of Africa, set in the Crown Jewels of Britain.