Strathclyde Police said two men, carrying what looked like a gun, raided Beaverbrooks in Glasgow Fort retail park.
The pair made off with a collection of Tag Heuer watches worth around £70,000 in the incident on Monday morning.
The robbers escaped in a silver Volkswagen Golf car, later found burnt out in Conisborough Road in Easterhouse, Glasgow.
Officers say they believe a second car was then used.
One of the robbers is white, 6ft 3in, slim and wore a grey hooded, zipped top with white drawstrings and dark bottoms. The second man is white, 5ft 8in, stocky and was wearing a black top of the same style, jeans and white trainers.
Detective Inspector Laura Thomson said: "I would urge anyone who saw anyone behaving in a suspicious manner at The Fort at around 11am on Monday, or saw the suspects enter or leave the premises to come forward. I am also anxious to speak to anyone who saw the Volkswagen Golf car driving from the scene."