Petra Diamonds reported that output for the nine months to March 31, 2013 jumped 20 percent to 1,894,767 carats while production for the third quarter of fiscal year 2013 rose 4 percent to 647,248 carats.

The miner said it was on track to meet its 2013 production target of around 2.65 million carats.

Revenue for the third quarter was 8 percent higher at $105.7 million. "The rough diamond market continued the firmer trend experienced since November/December 2012," Petra said.

"As usual, revenue will be weighted towards the full FY 2013 H2 period due to the seasonal timing of Petra’s diamond sales; two more tenders are to take place between through the end of the financial year-end."

Chief Executive Officer Johan Dippenaar said: “The company has delivered a solid operational performance in Q3, and we are focused on achieving our stated full year production target for FY 2013. Likewise, we are encouraged by the firmer trend within the rough diamond market, giving a positive outlook for the remainder of this financial year.”

Petra announced Regarding a 25.5-carat blue diamond discovered at the Cullinan mine in South Africa last month, the company said it is "considering the various routes to market for this exceptionally rare and valuable high quality stone and will update the market in due course."