Harare: Diamond exports fell by 34 percent to 5.9 million carats last year from the eastern Marange region after a slump in production, a junior government minister said.

Zimbabwe is one of the world’s top diamond-producing countries, and is believed to hold 25 percent of the world’s reserves of opencast extractable diamonds, with Marange fields its major diamond source.

The Marange diamonds are alluvial, lower quality stones compared with gems mined by Rio Tinto at its Murowa mine in south central Zimbabwe.

Fred Moyo, the deputy minister of mines told parliament that Zimbabwe’s exports were to Antwerp, Belgium and Dubai, while the government also held local auctions for foreign diamond buyers.

“This volume drop in sales reflects a drop in production, which is a result of transition from mining loose gravels to hard rock mining of conglomerates,” Moyo said. He did not give production figures for the period.

In 2014 diamond export earnings stood at $350 million compared with $453 million the previous year, he said. The government owns half the shares in all the mines in Marange and is planning to merge all diamond mining companies, including the Rio Tinto unit.

Moyo said the exercise to form one diamond company, in which the government would hold 51 percent shares, was expected to be completed later this year.