A 122.52 carat blue diamond has been discovered at Petra Diamonds' Cullinan mine, the company said on Friday.

"The rarity of a blue diamond of this magnitude sets it apart as a truly significant find," Petra said in a statement.

Last year, Petra sold a 25.5 carat blue diamond for US16.9 million (around R181.9m at the present conversion rate).

In May, Christie's auction house sold a 13.22 carat pear-shaped diamond, the Winston...read more here: 122.52 carat blue diamond discovered