A stolen Toyota Aqua reversed into the store on Broadway in the suburb of Newmarket about 8.55pm while several staff were closing up shop for the day.
Detective Sergeant Joseph Niupopo said the employees locked themselves in a back room while the offenders, whose faces were covered, began breaking cabinets and taking jewellery.
The thieves used hammers and tyre irons to get into the cabinets and fled with a large quantity of high-end pieces of jewellery.
Niupopo said officers found the car abandoned a short distance away with some of the stolen goods still inside.
Forensic examinations of the scene and vehicle were continuing.
Niupopo said none of the staff were injured but it was a distressing incident and police were providing them with support.
The employees made the right decision to put their own safety first, he said.
A stocktake of the store will be completed to establish what has been taken.
The public is being asked to contact police via 105 if they have any information related to the incident.
