Zimbabwe began selling diamonds worth more than £1 billion mined from an area where soldiers are accused of killing 200 people, raping women and forcing children into hard labour.
Heavily armed police and soldiers guarded top security vaults built at the main Harare airport, where several private jets brought buyers from Israel, India, Lebanon and Russia.
Abbey Chikane, Zimbabwe monitor of the world diamond control body, certified the diamonds ready for sale, saying they met minimum international standards.
Investigators said last year the gems were mined at the Marange diamond fields by virtual slaves who had been told to dig or die, and were smuggled out by soldiers who raped and beat civilians.
Yet the Kimberley Process, the diamond body, said those gems did not qualify as "blood diamonds."
Zimbabwe's mines ministry accuses human rights groups of "peddling falsehoods" over rights violations.
No estimated value was given for the stones, although unofficial estimates range up to £1.2 billion, a massive boost for Zimbabwe's ailing economy and representing about a third of its national debt.
The eastern alluvial diamond fields were uncovered in 2006 and are estimated to be able to meet a quarter of the world's demand for diamonds.
The find is described as the biggest in southern Africa since diamonds were discovered at Kimberley in South Africa a century ago.