Three men charged with receiving stolen jewels from armed robberies were nabbed with the help of listening devices and undercover agents, a Melbourne court has been told.
Colombian-born gold dealer Alejandro Mendieta Blanco and his brother Julio Mendieta Blanco, both 31, along with co-accused Chey Tenenboim, 36, faced Melbourne Magistrates Court on Monday.
Their appearance comes after police seized $3 million in assets including a Lamborghini convertible, gold bullion and precious stones from them last year.
The men, said to be pawn brokers, are all charged with receiving bracelets, watches, rings, precious stones and gold and silver jewellery, allegedly stolen by armed gangs during violent jewellery store raids.
They face 453 charges, including conspiracy to receive stolen goods and conspiracy to obtain a financial advantage by attempting to swindle customers.
Prosecutors claimed the men tried to "rip off" their customers by giving them fake information about how many carats their gold contained.
They say the trio was caught through listening devices in their shop, along with work by undercover operatives.
Police have 19,000 hours of phone recordings and 1200 hours of listening device material to analyse.
On Monday, prosecutors sought an adjournment so they had more time to work on a brief of evidence.
The court was told that during an upcoming committal hearing, a group of civilian witnesses would give evidence about how they'd had jewellery stolen.
A dozen others would testify they had stolen jewellery and sold it to the trio, or had provided jewellery without the items being officially registered.
The men, who are all on bail, will return to court on May 7 for a further committal mention.