The thieves left a bag marked "bomb" outside the store to slow police response, Swedish news agency TT reported Tuesday.
With the owner and his wife cowering in the back of the store, police said one suspect stood guard while two others put jewelry into a bag.
The suspects then left in a silver Volvo, police said.
About 30 minutes later, the car was found near a metro station, police said. Inside were the suspects' weapons -- and the jewelry.
No one was injured in the heist and police safely removed the suspected bomb.