Shortly after mid-day on Saturday, three unknown men walked into the luxurious Harry Hofmann shop in downtown Zurich and pulled a gun on two staff members, city police said in a statement.
"They stole numerous pieces of jewelry, gems and cash from the display and in an adjacent room. Shortly after they fled on foot ... with a booty worth well over one million Swiss francs", the statement said.
The two shop employees, a man and a woman, were not hurt, it said.
Zurich police had rushed to the scene, but were unable to apprehend the robbers.
They immediately launched a manhunt for the trio, and published security footage photographs of two of them, showing tall, dark-haired men both wearing glasses and trimmed beards, who both allegedly spoke broken German.
Police said the third offender could not be described in detail.