Firestone Diamonds' has announced "exceptional" results for its second diamond tender of 2011, held in Gaborone, Botswana and attended by buyers from over 31 local and international diamond companies.

A total of 14,248 carats of rough diamonds sold for some $2 million – a 42% increase in value over the company's April tender.

The lion's share of the diamonds (12,212 carats) sold in Gaborone originated from Firestone's Liqhobong Mine. The Liqhobong stones sold for an average per-carat price of $123, while diamonds from the mine's Main Pipe sold for $149/carat – price increases of 12% and 15%, respectively, from April.

The 2,036 carats of diamonds from Firestone's BK11 mine achieved a higher price than the Liqhobong stones, selling for an average of $235/carat, a 16% price increase from April.

Firestone Diamonds CEO Tim Wilkes said that the tender results reflected the continued strong demand for rough diamonds and the quality of production from Liqhobong and BK 11, noting that Liqhobong's diamonds continued to climb in value.