A 29.6-carat blue diamond, one of the rarest and most coveted in the world with a possible price tag of tens of millions of dollars, has been discovered at a South African mine by London-listed Petra Diamonds.
The miner said the "exceptional" acorn-sized diamond, small enough to fit into the palm of a hand, was unearthed at the Cullinan mine near Pretoria.
The mine, owned by Petra since 2008, was also where the Cullinan Diamond was found in 1905 — described as the largest rough gem diamond yet recovered and weighing 3,106 carats.
Other notable diamonds found in the mine include a 25.5-carat Cullinan blue diamond, found last year and sold for $16.9m, and a diamond found in 2008, known as the Star of Josephine, which was sold for $9.5m.
CEO Johan Dippenaar said the latest blue-diamond discovery could outstrip recent finds.
"By some margin ... this is probably the most significant stone we’ve ever, in terms of blue stones, recovered," he said.
"The stones in the past year or so are selling well above $2m per carat. That’s not my quote, that’s updates in the market," he said ahead of the company’s first-half trading statement.
Petra Diamonds is due to release figures on production and sales for the six months to December 31 on Thursday, but these will not take into account the latest find, which occurred in January.
Analyst Cailey Barker at broker Numis believes the diamond could fetch between $15m and $20m at auction.
Lately the owners of Petra diamonds refused to accept $12.500.000 offer for this stone.
Diamonds from both the Cullinan mine in South Africa and the Williamson facilities in Tanzania, both owned by Petra, have been displayed at London’s Buckingham Palace and are regarded as among the rarest and most valuable in the world.