"All I thought was gosh, what an amazing life Naomi Campbell has. Probably lots of men are always giving her diamonds and she said she was going to give it to Nelson Mandela's children's charity and I thought no more about it," Farrow said.
The donor relations manager for the Nelson Mandela Children's Fund, Mpake Pule, said there is no record the charity received a diamond from Campbell. She did make cash contributions of $50,000 that year and the year after, the charity officer said.
The Taylor trial has been underway for almost three years in the Hague.
Witnesses have included former Taylor deputies and some 50 victims of the terror campaign from Sierra Leone.
Taylor has strongly denied the prosecution's accusations that he "orchestrated" the atrocities in Sierra Leone.
"I resent that characterization of me," he testified. "It is false, it is malicious."