Grace Mugabe is suing a Zimbabwean newspaper over its reporting of claims released by Wikileaks she had made "tremendous profits" from the country's diamond mines.
The president's wife is demanding $15m (£9.6m) from the Standard newspaper.
The Marange fields in eastern Zimbabwe are said to be among the world's richest.
Army commanders and allies of President Robert Mugabe have been accused of profiting from diamond sales.
The Standard, a weekly paper, on Sunday reported the claims quoting a US diplomatic cable released by the whistle-blowing website, Wikileaks.
It quoted former US ambassador James McGee as reporting Andrew Cranswick, head of a British mining firm as saying: "There is a small group of high-ranking Zimbabwean officials who have been extracting tremendous diamond profits from Chiadzwa [mine]".
The cable names them as Grace Mugabe and Central Bank governor Gideon Gono, among other officials from the military and President Robert Mugabe's Zanu-PF party.
Mrs Mugabe's lawyer called the reports "false, scandalous and malicious".
"The imputation of such conduct on a person of such high standing, the mother of the nation, is to lower the respect with which is held by all right-thinking persons, to a point of disappearance," said the court summons, according to the state-owned Herald newspaper. BBC News
