Petra will receive an upfront payment of US$10.0mln for the Type IIa white diamond and US$3.5mln for the Type IIb blue stone as well as retaining a 50% interest in the profit uplift of the polished proceeds of both diamonds, after costs.
The diamonds were sold into a partnership with Stargems (Pty) Ltd.
“These two diamonds are wonderful examples of the very high quality and rare white and blue diamonds that are so well known from the Cullinan diamond mine,” said Petra Diamonds (LSE:PDL) chief executive Richard Duffy.
“We are delighted that both stones will be manufactured in South Africa and it is fitting that we will be working with Stargems, who specialise in the sourcing and supply of the finest diamonds to customers across the world.”
Petra Diamonds announced the discovery of the 342.92 carat white diamond last month.
The largest rough gem diamond ever found at 3,106 carats was from the Cullinan mine. The stone was cut into the two most important diamonds – the 530 carat First Star of Africa and the 317 carat Second Star of Africa – and are now part of the Crown Jewels in the Tower of London.