Petra Unearths 122.5-Carat Blue Diamond at South African Mine

June 13 (Bloomberg) -- Petra Diamonds Ltd. said it unearthed a 122.5-carat blue diamond at its Cullinan mine in South Africa, site of the discovery of the world’s largest gem 109 years ago.

Petra rose 5.3 percent to 176 pence by 8:07 a.m. in London trading, the highest intraday level for more than two years. The stone won’t be sold before its current financial year ends June 30, the company said in a statement.

The Cullinan mine is renowned for producing large blue diamonds, which sell for a premium. The company sold a 29.6-carat gem of that variety for $25.6 million in February and a 25.5-carat one for $16.9 million last year.

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.

“The stone will require further analysis in order to assess its potential value and upon completion of this process, Petra will be in a position to evaluate its optimal route to market,” the company said.

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To contact the editors responsible for this story: John Viljoen at Ana Monteiro