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 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 the firm since 2008, was also where the Cullinan Diamond was found in 1905—described as the largest rough gem diamond ever recovered and weighing 3,106 carats.
(Read more: South African miners treated as 'slaves': Union head)
Other notable diamonds found in the mine include a 25.5 carat Cullinan blue diamond, found in 2013 and sold for $16.9 million, and a diamond found in 2008, known as the Star of Josephine, which was sold for $9.49 million.