The 40-year-old supermodel will be asked to explain claims she received a "huge, uncut" `blood diamond` from former Liberian President Charles Taylor during a party held at former South African President Nelson Mandela-s house in September 1997.
Actress Mia Farrow - who has also been called to trial - claims the model personally told her about the precious stone.
Speaking from The Hague where a war crimes trial against Taylor is underway, a court spokesperson said: "What it is going to happen now is just a matter of when it happens."
Naomi has repeatedly refused to answer questions for the special court.
In April, Naomi reportedly grew visibly agitated when asked about receiving a "huge", uncut "blood diamond" from the dictator.
Campbell snapped: "I didn`t receive a `blood diamond` and I`m not going to speak about that."
Taylor has been on trial since 2008 for crimes against humanity, after a bloody campaign he waged in Sierra Leone between 1997 and 2001, during which time he is alleged to have been involved with `blood diamonds`.
A `blood diamond` - also called a `hot` or `war` diamond - is a jewel mined in a war zone and sold to aid warlord activity or invading forces` campaigns.