Johannesburg - Miner Petra Diamonds reported 20% higher core earnings for the first half, helped by production at its recently purchased Finsch mine.
Adjusted earnings before interest, taxes, depreciation and amortisation rose to $32.6m for the six months to December 31 from $27.1m a year earlier.
Petra, which has seven operating mines in South Africa and one in Tanzania, said revenue grew 63% to $151.7m.
The rough diamond market is expected to remain stable in the second half, the company said.
Earlier this month, the world's biggest diamond producer, De Beers, said a more positive outlook in China and India would boost sales of diamond jewellery in 2013.
Petra said last month that production rose 31% to 1.25 million carats for the first half, mainly due to the inclusion of output from the Finsch mine.
But it lowered its full-year production target by about 7%, citing uneven quality, particularly at its Finsch and Cullinan mines in South Africa.
Shares in Petra closed at 115.8 pence on the London Stock
Exchange on Friday. They have lost about 25% of their value in the past year.