The robbery happened at the Macy's at 401 S. Lake Ave., on Sept. 30 around 7 p.m.
Police say a man approached a salesperson at the jewelry counter and picked out a few items to look at as if he was a customer. When the clerk was scanning in the items for purchase, the man pulled out a silver-colored handgun and demanded the items, putting them in his own black bag.
He walked out of the store and it's not clear if a getaway vehicle was involved. Police say the jewelry was worth about $6,000.
The suspect is described as an African-American man, possibly in his 20s, standing about 5 feet 10 inches, weighing about 155 pounds, with black hair in a bun, wearing a white-and-pink striped shirt and red bandana on his head.
Pasadena police asked anyone with information to call Pasadena police at (626)744-4241 or provide an anonymous tip to Crime Stoppers at (800)222-TIPS.