It is alleged four males entered IMP Jewellery, on Toorak Road, just before 1pm on Saturday, January 14.

A shop assistant working that day was traumatised by the robbery, especially given it was her first day back at work following stress leave.

A male staff member was injured during the incident and a large quantity of jewellery was allegedly stolen before the males fled in a car.

A number of search warrants were executed at addresses in Shepparton, Mooroopna, Epping, Dandenong, Collingwood, Richmond and Preston.

Two 16-year-old Shepparton boys were arrested in Shepparton on January 19 and have been charged with armed robbery and possessing firearms.

They have been remanded in custody to appear at a children's court at a later date.

A further two 16-year-old boys from Epping and Richmond and a 17-year-old boy from Epping were arrested the following day and were each charged with armed robbery.

They will also appear before a children's court at a later date.

The arrests come after a taskforce was set up to investigate a recent string of jewellery shop thefts in Melbourne's most prestigious suburbs.

Assistant Commissioner Robert Hill said the investigation was ongoing.

"Police can assure the community that we are committed to investigating these incidents, identifying and arresting all those who are involved, whether it be those who plan or actively commit the offences," he said in a statement.