Johannesburg, South Africa (CNN) -- A friend of supermodel Naomi Campbell handed over unpolished diamonds to South African police the day that Campbell testified at a war crimes trial for former Liberian President Charles Taylor, police said Friday.
Police spokesman Musa Zondi told CNN that the diamonds are real.
Campbell testified Thursday at a United Nations-backed Special Court for Sierra Leone that she had received the diamonds as a gift, then turned them over to her friend Jeremy Ratcliffe to auction for charity.
She said on the stand she believed Ratcliffe still had the stones. Zondi said Ratcliffe could face charges of possession of unpolished diamonds.
Campbell said she was handed the stones following a dinner hosted by Nelson Mandela in 1997.
"When I was sleeping, I had a knock on my door. I opened the door and two men were there. They gave me a pouch and said, 'A gift for you,'" the supermodel testified.
The men didn't introduce themselves or say anything else, Campbell said.
The next morning, she opened the pouch and saw a few "very small, dirty-looking stones."
Prosecutors are trying to prove that Taylor used so-called blood diamonds to fuel a brutal civil war in neighboring Sierra Leone.
Taylor, 62, was president of Liberia from 1997 to 2003. The war crimes charges against him stem from the widespread murder, rape and mutilation that occurred during the civil war in Sierra Leone, fought largely by teenagers who were forced to kill, given addictive drugs to provoke violent behavior, and often instructed to rape and plunder.
Taylor is charged with five counts of crimes against humanity, including murder, sexual slavery and violence, and enslavement. He also faces five counts of war crimes, including acts of terrorism and torture, and one count of other serious violations of international humanitarian law.
He has pleaded not guilty.
Prosecutors had rested their case against Taylor in February 2009 but reopened it to call Campbell to testify after learning in June of that year that Taylor had given the supermodel a diamond.
When arguing to reopen the case, prosecutors said Campbell's testimony would prove that the former president "used rough diamonds for personal enrichment and arms purchases," according to papers filed with the U.N.-backed court.
Taylor has testified that he never handled the precious stones.
Campbell told the tribunal Thursday that she shared the story of receiving the stones with her former agent Carol White and the actress Mia Farrow at breakfast the following morning.
"Well, that's obviously Charles Taylor," one of them said. Campbell didn't recall who said it. Then, one of them added, "Well, obviously, they are diamonds." Campbell said she assumed the stones came from Taylor.
Campbell said passed the stones to her friend, Jeremy Ratcliffe, and asked him to use the stones in a charity auction to raise money for underprivileged children.
Ratcliffe is a trustee of the Nelson Mandela Children's Fund, which denied hours after Campbell's testimony that it had ever received diamonds from her.
Future witnesses at the war crimes trial are likely to dispute Campbell's story, prosecutors said after her testimony.
"Two other witnesses will also testify about these events.... there are significant differences between those accounts and Ms. Campbell's account," the prosecution said in a statement.
It did not name the witnesses, but court papers show prosecutors plan to call Carol White and Mia Farrow.