Petra Diamonds said on Monday it had recovered an extremely rare 20.08 carat blue diamond from its flagship Cullinan mine, the world's main source of rare blue diamonds.
The diamond miner has invested heavily in the South African mine as it bets on big finds in an industry assailed by synthetic rivals and uncertain demand despite being saddled by debt.
Petra bought Cullinan in 2008, aiming to breathe new life into one of the world's most famous diamond mines renowned for yielding the largest 3,106 carat rough gem diamond ever found in 1905.
In 2015, Petra sold "The Blue Moon of Josephine", a 29.6 carat blue diamond, for $48.5 million, marking a world record price per carat for any diamond at the time, according to its website.
Cullinan accounted for around a third of the company's diamond sales revenue in 2018.
Shares of the company pared losses after the news and were flat as of 1333 GMT.
