|Naomi Campbell met Charles Taylor at a dinner in South Africa in 1997 [AFP]
Naomi Campbell, the British model, has taken the stand at the war crimes trial in The Hague, the Netherlands, of Charles Taylor, the former Liberian president.
Al Jazeera examines why her testimony could be crucial for the case.
What is Charles Taylor on trial for?
Liberia's former president is facing 11 counts of war crimes and crimes against humanity for his alleged role in the 1991-2002 Sierra Leone conflict, which claimed hundreds of thousands of lives.
The charges include instigating murder, rape, mutilation, sexual slavery and conscription of child soldiers.
He is also accused of receiving illegally mined "blood diamonds" in return for arming rebels who murdered, raped and maimed civilians in Sierra Leone.
Taylor, 62, has denied all the charges.
His trial is taking place at the Special Court for Sierra Leone in The Hague, the Netherlands, an independent judicial body established with backing from the United Nations Security Council.
The court issued an indictment against the former president in 2003, but he was not brought to trial until the beginning of 2008.
Taylor is the first former African head of state to face an international tribunal on charges of crimes against humanity.
Why is Naomi Campbell's testimony important to the trial?
Prosecutors called Campbell to the stand in the hope that she would provide evidence that Taylor was in possession of uncut diamonds, which he is alleged to have received in return for providing guns to rebels.
The model allegedly received the diamonds in 1997 after a dinner hosted by Nelson Mandela, the former South African president, in Cape Town at which Taylor was also a guest.
Her gift came under scrutiny after Mia Farrow, a US actress and another guest at the dinner, claimed that Campbell had received the diamonds from the former Liberian leader.
Did her testimony provide a link?
Campbell did not appear to give conclusive evidence linking Taylor to the diamonds in her appearance at court on Thursday.
She said she had received some "dirty-looking stones" but was unsure whether they were actually diamonds and said she did not know who had given them to her.
"I thought they were dirty looking pebbles," she told the court.
"I'm used to seeing diamonds shiny and in a box ... If someone had not said they were diamonds, I would not have known they were diamonds."
Tim Friend, Al Jazeera's correspondent at the Hague, said: "I think the main link which the prosecution were trying to establish - between Charles Taylor, blood diamonds, Naomi Campbell, seeking profit to buy weapons for those rebels in Sierra Leone during that terrible, bloody conflict - that has not been proved conclusively as a result of her evidence today".
However, Annie Dunnebacke from Global Witness, an international investment watchdog based in London, said she believed a link had been made.
"Naomi Campbell has testified that she received diamonds [after] an event where Charles Taylor was present," said Dunnebacke.
"It's difficult to assess right now what the significance is for the prosecution but certainly this trial is of huge significance to the people of Liberia and Sierra Leone."
Dunnebacke said her organisation believes that Taylor was "bank rolling the Revolutionary United Front (RUF) rebel group in Sierra Leone by taking the diamonds that were being mined them and selling them onto the international markets".
"The money that was made from these sales was used to buy guns, ammunition, that was then funnelled back to the rebel group in Sierra Leone," she said.
Campbell did provide one possible lead on the diamonds - that she had passed them onto Jeremy Ratcliffe, the-then director of the Nelson Mandela Children's Fund, in an attempt to help the charity.
She told the court that when she last spoke to Ratcliffe in 2009 he was still in possession of the rocks.
What are "blood diamonds"?
"Blood diamonds" are uncut or rough diamonds illegally traded to help finance conflicts in war-torn areas, primarily in central and western Africa, where diamonds are mined.
The United Nations defines them as "diamonds that originate from areas controlled by forces or factions opposed to legitimate and internationally recognised governments, and are used to fund military action in opposition to those governments, or in contravention of the decisions of the Security Council".
What is the Kimberley Process?
In 2003, an international certification scheme for rough diamonds, known as the Kimberley Process, was set up to stop the trading of "blood diamonds".
Dunnebacke said the scheme puts controls on the rough diamond trade to prevent them from fuelling conflicts.
"Certainly it's brought increased transparency to some sections of the diamond industry - it's helped diamond revenues in some African diamond-producing countries," she said.
"But it's still riddled with weaknesses, and in large part it's down to the member governments and the diamond industry to close the loopholes, make the scheme work more effectively and prevent the blood diamonds that are currently reaching international markets from being exported."
At the height of the civil war in Sierra Leone, it is estimated that conflict diamonds represented approximately four per cent of the world's diamond production.