Police in Australia are hunting a thief who smashed his way into an exclusive jeweller and snatched a $1m diamond ring.

It was a brazen attack that took place in broad daylight on Sunday afternoon.  The Herald Sun reports that the robber approached the store, dressed in black and wearing a skin-tight beanie over his head, and then proceeded to smash the display window using a minature sledgehammer.

The store, Hardy Brothers Jewellers on Collins Street in Melbourne, was still full of staff who were busy closing up at the end of the day.  But the glass was so thick that they didn’t realise exactly what was happening at first.  The thief swung the hammer several times before successfully punching a fist-sized hole in the display window and then reaching inside to snatch the precious diamond ring.

The ring was of a simple solitaire design, a claw setting featuring a single round ‘brilliant cut’ diamond.  It’s the size of the stone that makes this piece special: 9.10 carats.

It was known as the ‘Million Dollar Ring’, but it didn’t carry a price tag – it was on display as the centrepiece in the shop window and was being featured as a promotional item for the jeweller.

Police in Melbourne are studying CCTV and appealing for witnesses. At least 15 people are said to have been waiting at a tram stop just outside the store.  Police are also also asking whether anyone sold a 1.8kg ‘baby’ sledgehammer in recent days.