A masked robber took only seven seconds to smash a hole in a display window with a sledgehammer and make off with a diamond ring worth HK$5.26 million (US$677,455) from a jewellery shop in one of Hong Kong’s busiest shopping districts on Friday.

Police say that after the daring daylight Hong Kong smash-and-grab raid, the man ran into a nearby alley and entered a toilet where he discarded his cap, sunglasses, gloves and face mask and changed into different clothes and shoes before fleeing.

Police are still searching for the non-Chinese man, who was last seen wearing a jacket, red shirt, light-coloured trousers and red shoes.

“Initial information showed the stolen ring was the most expensive item in the display cabinet,” says a police source. The raid happened at the Tsim Sha Tsui branch of the 3D-Gold jewellery chain, on the ground floor of Hai Phong Mansion, shortly after 11am.

An online video shows the lone culprit hitting the display window six times to break it before grabbing the ring and dropping the 50cm-long hammer.

Police have seized a cap, blue surgical mask, sunglasses, black gloves, a black windbreaker, black trousers and a pair of sports shoes the robber discarded in a toilet inside a tea house off an alley less than 100m from the shop.

A 3D-Gold spokeswoman says the raid happened about half an hour after the shop opened. The stolen item is a 6.6-carat diamond ring, she says.

On the first day of the Lunar New Year, January 28, two non-Chinese men made off with more than 30 watches worth HK$1 million from the Montblanc shop in the IFC mall in Central after breaking open the shop’s glass door with a sledgehammer and smashing three glass showcases.

Police figures show there were 260 reports of robbery last year, a 16.6 per cent rise compared with 223 cases in 2015.