Zimbabwe has held the first sale of diamonds from its Marange fields since the body overseeing the trade in "blood diamonds" lifted a ban.
The Kimberley Process had suspended the diamond exports in November in response to allegations of atrocities committed by the military at Marange.
But last month, it ruled that abuses had ceased and said Zimbabwe could resume limited exports.
The diamonds from the Marange field could generate $1.7bn (£1.1bn) a year.
About 900,000 carats valued at about $72m were on sale on Wednesday, according to Abbey Chikane from the Kimberley Process.
A review of conditions at Marange will be carried out in September, after which Zimbabwe may be able to resume full exports.
The Kimberley Process was set up in 2002 after the diamond trade was accused of fuelling several conflicts in Africa.
The BBC's southern Africa correspondent Karen Allen said the credibility of the Kimberley Process had been at stake over the Marange diamond fields, with pressure to expel Zimbabwe from its certification scheme.
Questions had been raised about the competence of its own independent monitor, she said.
In opening the sale, Prime Minister Morgan Tsvangirai said: "Indeed it is historic in that we have managed to satisfy the minimum requirements of the Kimberley Process.
"We have put in place measures to ensure that we abide by the Kimberley Process principles and sell our diamonds in a transparent manner."
Irene Petras, a human rights lawyer, told BBC World Service's Focus on Africa programme she was disappointed that the sale had been allowed.
"What's disappointing is that, although the sale's going ahead, we still haven't received any information about how human rights violations will be investigated and also how accountability will occur in terms of the sales of these diamonds," she said.
And human rights groups expressed fears after President Mugabe urged the army to "jealously guard" the country's natural resources in a speech on Tuesday.