One of the youths, a 17-year-old from Dandenong South, was charged with one count of armed robbery and remanded in custody to appear at the children's court.

The other, an 18-year-old from Epping, was charged with six counts of armed robbery, among other offences. He is due to appear at the Melbourne Magistrates Court on Friday.

Three other men were also arrested: an 18-year-old from Craigieburn and a 19- and a 20-year-old from Reservoir. After being interviewed by police, they were released pending further enquiries.

The heist took place in broad daylight on Thursday, when three masked men allegedly stormed into Holloway Diamonds on Canterbury Road, Canterbury at 1.30pm.

The staff reportedly hid in a back room of the store, while the thieves smashed open display cabinets and filled a sack with jewellery.

No one was injured, but a large quantity of jewellery was said to have been stolen.

The robbery was the latest in a series of violent robberies across Melbourne where jewellery stores have allegedly been targeted by machete-wielding thieves .

• Three masked robbers armed with a handgun and machete robbed H&H Jewellery on Glen Huntly Road, Elsternwick, in the afternoon of January 4. Police said the gang had threatened staff and took  jewellery before leaving in a waiting vehicle without registration plates. An employee of the business, which also has stores in South Yarra and Collins Street, said they were shaken by the robbery.
• A Toorak store, IMP Jewellery, was held up by three men with a gun, machete and hammer in October. The store's manager was labelled a hero after he ushered two employees to safety before refusing to open the safe while a gun was pointed at his head. He then pushed the men out of the shop.

Police investigators do not currently believe the suspects in the Canterbury theft are related to the Elsternwick and Toorak robberies.

Police urge anyone with information to contact Crime Stoppers on 1800 333 000 or submit a confidential crime report to www.crimestoppersvic.com.au.