The prosecution hopes that Naomi Campbell's testimony at the Hague will prove to be vital evidence that links "blood diamonds" to the defendant Charles Taylor, the former warlord and Liberian leader.
Prosecutors summoned the supermodel to support their allegations that Taylor received blood diamonds from rebels in Sierra Leone and used them to buy weapons, which he allegedly shipped from Burkina Faso to the Sierra Leone junta in October 1997.
The 62-year-old, who denies all 11 charges against him, is accused of arming and controlling Sierra Leone's Revolutionary United Front (RUF), a rebel force responsible for widespread atrocities, including using child soldiers as young as 10 to carry out massacres.
Prosecution lawyers hope that Campbell has said enough to show two things: that Taylor was in control of the diamonds at the relevant time, and that they were the same rough-cut gemstones mined in Sierra Leone.
But this will not be easy. Taylor's defence team has already identified "weaknesses" in the model's testimony. Significantly they say that the model says that Taylor did not personally hand her the "stones" which she had no way of knowing were diamonds rather than any other sparkling gem. The prosecution's case suffered a further setback yesterday when the very existence of the gems was thrown into doubt. Campbell said that she gave the "stones" to Jeremy Ratcliffe of the Nelson Mandela Children's Fund because she wanted them to go to charity – and that when she spoke to Mr Ratcliffe on the telephone in 2009 he said he still had them.
But in a letter presented in court by the defence, the Nelson Mandela Children's Fund said it had never received a diamond or diamonds from Ms Campbell or from anyone else.
Now attention will turn to the evidence of the supermodel's former agent Carole White and the actress Mia Farrow, who both say Campbell told them after the charity dinner that she had received the diamonds from Taylor. Farrow has already described Campbell's account as "unforgettable". They are due to give their testimony next week.