The mine had been abandoned and its holding company had closed since November last year, hamstrung by outdated equipment and further hit by the fall in global diamond prices.
The company, which employed 5,000 people, produced an average of six million carats annually at the start of the decade.
Production fell to one million carats in 2007 and less than 500,000 carats
The state holds an 80 per cent stake in the firm. The remaining 20 per cent belongs to Mwana Africa, a South African company.