Mpofu is leading a Zimbabwe delegation which includes officials from the Zimbabwe Mining Development Corporation and civil society organisations linked to Zanu PF.
Western diplomats said the US had temporarily lifted travel sanctions on Mpofu to allow him to attend the diamonds indaba.
In 2001 the US and the European Union slapped President Robert Mugabe and about 160 members of his inner, including Mpofu, with targeted sanctions that, among other things, bar them from travelling and transacting in the United States.
The KPCS intercessional meeting opens in Washington DC on Monday and ends Friday.
Mpofu told Radio VOP before his departure that he was confident that people against Zimbabwe’s trade in Marange diamonds will be disappointed after the meeting.
“I was personally invited by Gillian Milovanovic, the Kimberley Process chair, and I am sure they now understand our position especially the fact that Zimbabwe does not have blood or conflict diamonds,” said Mpofu.
“In fact, we are not going to entertain any politics on so-called human rights abuses. We have taken journalists and human rights activists to Marange and they have not seen any abuses.
“Nothing has been written by journalists that went there on the so-called human right abuses because there are no such violations in Marange,” he said.
“I am confident we are going to have a successful meeting.” Mpofu and his team are expected back in Harare next Sunday.