The theft happened on February 3 at the store on the 8500 block of Henry Avenue.
Surveillance video shows the suspect walking into the store after 7 p.m.
He approaches the jewelry counter and asks the employee to look at a specific diamond ring.
As the employee was handing him the ring to look at, he grabs it and takes off.
The ring was a Cherish Always diamond ring valued at $4,999.
The suspect is described as a black male in his early to mid 20s with a light complexion and light beard/goatee. He was wearing a white knit hat with a blue stripe, a red, white and blue jacket, faded blue jeans with holes in the legs and white Nike sneakers.
If you have any information on this theft, call Northwest Detectives at 215-686-3353.