Petra Diamonds warns of full year profit concerns

The miner's increased sales in the period was in part thanks to the sale of two exceptional diamonds for a combined revenue of $38.7m.

However, first half production decreased 2% to 1,601,069 carats.

In its trading update the mining outfit explained that in the reporting period the market for rough diamonds had been softer than usual.

Nonetheless, the company increased its full-year production guidance from approximately 3.2 Mcts to about 3.3 Mcts.

Despite that, Petra Diamonds warned that adjustments to its estimates for diamond grades and pricing may lead to full-year results coming in below the current market consensus.

To take note of, the weaker Rand - South Africa's currency - is also currently having a favourable effect on Petra's operating costs in US dollar terms.

Costs remain well controlled and in-line with guidance. At $125.2m the firm's capital expenditures were also in-line.

Net debt had decreased sharply by 31 December 2014, to stand at $45.8m versus the $108.8 at the end of the prior year.

The company's cash position came in at $129.6m, while its $66.9m in debt facilities were undrawn and available.