Actress Mia Farrow has testified that model Naomi Campbell said she got a "huge diamond" from men sent by ex-Liberian president Charles Taylor.
Ms Farrow's testimony directly contradicts Ms Campbell's account that she received two or three stones and did not know who sent them.
Linking Mr Taylor to illegal "blood diamonds" is key to the prosecution's case at his war crimes trial in The Hague.
Mr Taylor denies all 11 charges.
He is accused of war crimes during Sierra Leone's civil war, including using the diamonds to fund rebels.