Rights groups, which accuse Zimbabwe’s security forces of committing widespread atrocities in a bid to stop thousands of illegal diamond miners who descended upon the poorly secured fields in the eastern part of the country, have been pushing for a ban on Zimbabwean diamonds.

The Kimberley Process Certification Scheme — which regulates the global diamond trade — voted last November to allow Zimbabwe to continue mining and trading in diamonds, but gave it six months to improve conditions in Marange.

The government, through its mining arm Zimbabwe Mining Development Corporation, has partnered little-known South African companies, Core Mining and Grandwell Holdings, to set up Mbada Diamonds, a joint venture firm which is mining diamonds in Marange.

Mbada Diamonds chairman, Robert Mhlanga, told the state-controlled Herald newspaper that about 300,000 carats worth of diamonds would be auctioned in Harare on Thursday.

International diamond buyers from the Americas, Europe Asia and Africa would take part in the auction, Mhlanga was quoted saying.

"This inaugural sale will be followed by a similar sale of another 300,000 carats next week, following about a month of mining operations at Mbada’s…Marange diamond fields," Mhlanaga said.

"The entire process of mining, transportation and marketing is being done in compliance with the requirements of the Kimberley Process."

The Zimbabwe government would earn up to 80 percent of the proceeds from the diamond sales, the newspaper added. 

The Marange diamond fields are at the centre of a legal dispute between the Zimbabwe government and London-listed African Consolidated Resources (ACR), whose claims were cancelled by the authorities in 2006.

The government has ignored a High Court order, issued last September, to restore the Marange claims to ACR.

Other players in Zimbabwe’s diamond mining industry are Rio Tinto, whose Murowa is the country’s largest diamond mine in, and the privately run River Ranch mine.