Mr Milo followed the man and snatched his bag through an open car window.
He then started sprinting to the nearest police station, about 100m away.
His actions clawed back about $50,000 worth of jewellery, but the alleged robber still managed to get away with handfuls of necklaces, bangles and bracelets.
"I can only imagine what it must have been like for that girl in the shop. My heart was racing," Mr Milo said.
Gold Merchants managing director Pravin Kumar said the offender had threatened the shop assistant at Lotus Gold Jewellery and ordered her to lie down.
"He then broke into the display cabinet, taking a substantial amount of high value gold jewellery."
Mr Kumar released CCTV footage of the incident last week as part of an appeal for information.