Maseru - Miner Gem Diamonds said it recovered a 100 carat diamond from its Letseng mine in Lesotho, sending its shares up as much as 8%.
The discovery of the rough diamond on June 22 is the third diamond of over 100 carats in size to be recovered from Letseng since May. A 164 carat diamond from Lesotho sold for $9m last month.
"The recovery of three diamonds each with a likely price-tag in the $6m to $10m range should be viewed against total 2012 revenue of $202m," Citigroup analyst Jon Bergtheil said.
"The three diamonds alone could come to represent more than 13% of 2012 turnover," he said.
Letseng's June export achieved an average price of $2 087 per carat, for a total value of $22m, compared with an average price of $1 599 per carat for the first three tenders in the year, Gem Diamonds said in a statement.
"Mining will steadily increase in the higher value and higher grade satellite pipe in the second half of this year, and it is anticipated that revenues will therefore show a resulting increase," chief executive Clifford Elphick said.
Shares in the miner were up 6% at 120 pence in early trading on Wednesday on the London Stock Exchange.