That the first witness is a conflict- or blood-diamond expert, underscores the heart of the prosecution's case - that Charles Taylor terrorized neighboring Sierra Leone in order to appropriate its diamond wealth for his own ends.
Taylor looked relaxed as Canadian Ian Smillie took the stand and told judges why African leaders like Charles Taylor needed the diamonds. He called the gemstones the "most concentrated form of wealth on earth."
"They are very small, they are high value, they are easy to move, they hold their price, historically they have held their price very well," he said. "So they have become a - not so much today, but in the 1990s, the period we are talking about - they were an alternative to hard currency in countries where there was no hard currency or where people wanted to hide the movement of money."
Smillie says Sierra Leone has far more - and better quality - diamonds than Liberia, which is where Charles Taylor ruled, but not where his alleged crimes were committed. Judges saw photos of an airplane filled with crates that allegedly contained weapons smuggled from the Ukraine into Liberia, despite a U.N. arms embargo on the country.
Smillie says Charles Taylor told him he had nothing to do with trafficking in stolen diamonds, that many people misused Liberia's name to smuggle them, and it was out of his control. But defense lawyers tried to discredit some of Smillie's other testimony as gossip and rumor.
Smillie is one of eight experts expected to testify in the coming months, along with former Taylor associates and victims of the militias he allegedly supported. Those armed groups became infamous for hacking off limbs.
Taylor, who boycotted the start of his trial in June, saying it would not be fair, has been getting about $100,000 a month from the court for his defense, despite beliefs he is hiding a fortune.
Prosecutors have 144 witnesses lined up - half are expected to testify here, and half in writing. They have to prove that Mr. Taylor supported the rebels in neighboring Sierra Leone in their terror campaign, in which tens-of-thousands of people were killed.