Prosecutors say the event is significant because it directly links Taylor to such uncut diamonds. One of the allegations in the case is that Taylor was in South Africa at the time to buy weapons for the Sierra Leone rebels with "blood diamonds."
Under cross examination at the trial, Taylor repeatedly denied he had a large quantity of diamonds or that he sent one to Naomi Campbell.
"Total nonsense," Taylor testified when asked if "that diamond that you sent Naomi Campbell was one of the diamonds that you had been given by the junta in Sierra Leone."
"And those diamonds, along with money given to you by the junta were to be used to procure weapons for the junta?," the prosecutor, Brenda Hollis, then asked.
"Totally incorrect," replied Taylor.
Prosecutors had hoped Campbell could rebut Taylor's denials.
Despite Campbell's refusal to help prosecutors, and her denial to ABC News that she received a diamond from Taylor, actress Farrow says "there's no doubt in my mind" of what happened.
"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."
The prosecution has already presented its case, and in order to admit the newly discovered photo in evidence, would have to ask the judges to reopen the case. Hollis said she had not yet decided whether to make the request, or whether to subpoena Campbell as a witness.
However, the judges had previously disallowed Farrow's testimony about what Campbell allegedly told her. According to Hollis, the judges also said that whether or not Campbell had received such a diamond was "central" to the case against Taylor.
"The judges have said that this is very important to our case, so it's something we would consider," said Hollis. "We haven't made any decisions but we certainly are considering options in that regard."
Hollis said that if Campbell were subpoenaed as a witness, enforcing the subpoena would require that her country of residence give assistance to the court. The Special Court for Sierra Leone of the International Criminal Court is in the Netherlands. Campbell lives in Moscow with her boyfriend.
"You always have the option of asking people if they will come voluntarily," said Hollis. "You have the option of subpoena -- you would need the assistance of the state.
Naomi Campbell's attorney and spokesperson did not respond by presstime to a request for comment.