A Belgian court Monday sentenced eight people for up to six years in prison for smuggling conflict diamonds from Africa into the port city of Antwerp, the world’s largest diamond center, Reuters reports.

The Antwerp criminal court also fined them $81.77 million for not declaring the diamonds to customs, a court official told Reuters.

It sentenced ring leaders Samih Ossaily and Aziz Nassour to three and six years in jail, respectively, Reuters reports.

It accused Ossaily, 38, and Nassour, 43, of respectively importing diamonds from conflict areas in Sierra Leone and the Democratic Republic of Congo some fours year ago, Reuters reports.

Ossaily denied he smuggled diamonds from Sierra Leone.

“I … deny that,” he reportedly told local VRT television. “(They came) from Liberia. It was during the time there was no embargo.”

Countries that import diamonds ban stones from countries in conflict because the proceeds from their sale often finance these wars.

The court gave sentences of up to 30 months in prison for the six other members of the ring.

JCK