The trial of 19 suspects believed to be involved in a spectacular $50mn diamond heist at Brussels airport in 2013, opened on Wednesday in the Belgian capital.
The February 2013 robbery, one of the world's biggest diamond thefts, saw a gang of armed men posing as police seize the gems from a passenger plane in an operation that lasted barely 10 minutes without a shot being fired.
The hooded men, armed with machine guns, pulled up in a car on the runway at Brussels' main Zaventem airport where an armoured vehicle had just unloaded diamonds into a plane about to take off for Zurich.
The men forced open the hold and removed about 120 boxes of diamonds before making off with the haul of about $50mn in gems, most of which was never recovered.
More than 30 people were detained in Belgium, France and Switzerland in massive coordinated police operations.
The arrests included the main suspect, the Frenchman Marc Bertoldi, who is currently being held in France.
He will not attend the trial in Belgium, which is expected to last until the end of next week.
Before the airport heist, Belgium had already experienced spectacular robberies involving diamonds and precious gems.
In February 2003, jewellery and diamonds valued at around 100 million euros were stolen from an Antwerp diamond exchange.
More than 120 safes in the port city's Diamond Center, a heavily protected building in the heart of the diamond district, were emptied unnoticed.