Gem Diamonds Limited has found a 12.47-carat blue diamond and an 83.8-carat, exceptional quality, white diamond at the Letšeng mine in Lesotho.
Both of the stones "are expected to fetch good prices" at Letšeng's tenders to be held in Antwerp, the firm said.
The blue stone was recovered from the main pipe, while the 83.8 carat white diamond was found at the satellite pipe.
Gem Diamonds CEO, Clifford Elphick said: "Letšeng continues to recover large, white, largely undamaged diamonds on a relatively consistent basis as well as the occasional rare blue or pink diamond.
"As mining focuses on the higher value and higher grade satellite pipe during the latter part of this year, it is expected that Letšeng will continue to produce more of these exceptional diamonds," he added.
