Johannesburg: Petra Diamonds said revenue leapt 48 percent in the first fiscal half because of steady demand following a stabilization in the rough market.

Sales grew to $228.5 million during the six months that ended December 31, the miner reported. Excluding ‘exceptional’ diamonds, revenue rocketed 51 percent from a year ago to $217.6 million. Total sales by volume jumped 47 percent to 1.9 million carats.

The increase in revenue comes as rough-diamond prices have been flat during the period on a like-for-like basis, the company said. The miner also highlighted an improvement in retail demand, citing pockets of growth among retailers such as Tiffany & Co., Luk Fook and Birks Group during the 2016 holiday season and noted improved sales in China. Petra expects market conditions to remain stable in the second half of its fiscal year that ends June 30.

“Signs of stabilization in the rough diamond market are evident with steady demand across the majority of size ranges,” the company said.

The one exception to this upwardly trend is that smaller, lower-value categories of rough diamonds saw demand slip because of the Indian government’s decision to invalidate INR 500 and INR 1,000 currency notes, the company explained. This policy, known as demonetization, has sapped liquidity from the hands of smaller diamond manufacturers.

“We expect this situation to improve in the short term,” Petra’s chief executive officer Johan Dippenaar said.

Petra’s rough production jumped 24 percent to 2 million carats due to a higher concentration of diamonds in the ore. Output increased 30 percent at the Cullinan mine in South Africa and climbed 12 percent at the Williamson project in Tanzania. This outweighed a 6 percent drop at the Finsch deposit in South Africa due to a planned cut in production. Diamond recovery also slumped 22 percent at Koffiefontein in South Africa.