Supermodel Naomi Campbell has told the war crimes tribunal of former Liberia president Charles Taylor that she was given a few "dirty-looking" stones.
Ms Campbell is being asked about allegations that Mr Taylor gave her "blood diamonds" as a gift in 1997, the BBC reports.
Prosecutors in The Hague say her evidence could help link Mr Taylor to the stones, which they say he used to fund the civil war in Sierra Leone. He denies the charges and says he never sold or traded diamonds for weapons.
Ms Campbell, who was late appearing in the courtroom, swore on a Bible before beginning her testimony.
She told the court: "I saw a few stones, they were very small, dirty-looking stones," adding that she did not know who the diamonds were from.
When asked by the prosecutor how she knew they were diamonds, she replied: "I don't know, because they were in a jewellery box."
Allegations that the rough, uncut gemstones were given to Ms Campbell emerged in a statement by American actress Mia Farrow.
Ms Farrow claimed that Ms Campbell had told her she had been given the stones after a celebrity dinner in South Africa, hosted by former South African President Nelson Mandela.
Ms Campbell is said to have donated her gift to Nelson Mandela Children's Fund, although the fund told a British newspaper it had not received any stones from the model.
Ms Campbell is a reluctant witness and has been subpoenaed to appear by prosecutors or risk contempt of court charges.