A world diamond network has vowed to expel any member who knowingly trades gems from two Zimbabwe mines where labourers have been killed and children enslaved.
The announcement by US-based Rapaport Diamond Trading Network, an industry diamond price and information provider, is being hailed as an unprecedented move that will boost buyer awareness of blood diamonds.
It comes after international regulators declared the stones from the Zimbabwe mines conflict-free, backing off a ban they imposed in November and allowing 900,000 carats of diamonds to be auctioned last week.
"This is the first time that we've heard of a large group like the Rapaport group actually taking such a strong stand," said Tiseke Kasambala, a Zimbabwe specialist with Human Rights Watch.
The international regulators, whose group is known as the Kimberley Process, said the two mines were operating at "minimum" international standards.
The Rapaport group, though, said that did not guarantee the stones "free of human rights violations" and vowed to publish the names of members knowingly trading in diamonds from the diamond fields near the eastern city of Mutare.
Kimberley Process officials did not immediately respond to an email seeking comment on the move by Rapaport, which has 10,000 members.
The Zimbabwe Ministry of Mines accuses human rights groups of "peddling falsehoods". The auctioned diamonds are expected to provide millions in badly-needed revenue for the southern African country.
Robert Mhlanga, head of diamond mining holding company working alongside the government, said offers were made at the first auction on August 11 for all 900,000 carats cleared for sale by the Kimberley Process.
The party of prime minister Morgan Tsvangirai, Zimbabwe's former opposition leader now in a shaky coalition with long-time president Robert Mugabe, has warned against raising hopes of a rapid economic boom.