The shop is only about 12 feet wide and about 20 feet deep and had jewelry cases hanging on the walls. No customers were believed to be in the store at the time, police said.
The gunman took off south on Madison Avenue, and police were still looking for him. The victim was taken to Lenox Hill hospital with a chest wound and was later pronounced dead.
The neighborhood boasts rows of swanky boutiques and expensive jewelry shops and the incident occurred not far from the Whitney Museum of American Art. The area near the shop was cordoned off with yellow crime scene tape, but traffic was moving along Madison Avenue.
Carmen Fontanez, a private security guard who patrols the stretch of Madison Avenue, said a man was smoking in front of the store when a tall man wearing a ski mask and sunglasses pushed him inside and shut the door behind him.
The shooting happened very quickly, she said.
Other shopkeepers said R.S. Durant is a relatively new store and was about a year old.