Johannesburg - London-listed diamond miner Petra Diamonds said on Monday it expected full-year results below analysts' average forecast, citing softness in the diamond market.
The miner, which has four producing mines in South Africa and one in Tanzania, revised its full-year production guidance to about 3.3 million carats from about 3.2 million carats.
Shares in the company fell up to 9% on the London Stock Exchange.
Analysts on average had expected full-year pretax profit at $188.84m, on revenue of $532.01m, according to Thomson Reuters.
Due to the softness in the diamond market, Petra lowered its full-year guidance for the Finsch, Cullinan and Koffiefontein mines.
It estimates that diamond prices on a like-for-like basis were down on average by 8% to 9% in the first half ended December 31.
Petra reported a 16% jump in first-half revenue to $214.8m, helped by sales proceeds for two exceptional diamonds for combined revenue of $38.7m.
The company said it would pay a maiden dividend of 2 pence per share for the 2015 financial year.
Shares in the miner were down 8% at 166.10 pence at 10:06.
In July 2014 Petra Diamonds said full-year production jumped 17%, driven by higher output at its Finsch mine in South Africa.
Petra said at that time that production rose to 3.1 million carats in the year ended June 30 from 2.7 million a year earlier.