The incident was reported at a residential building on 1st Avenue and Cooper Road on Wednesday afternoon.
The 86-year-old victim was waiting for an elevator when the suspect forcibly grabbed her chain and pulled it off her neck after a brief struggle.
ALSO READ | Car careens into outdoor dining area, injures woman in Brooklyn
The necklace had a value of about $2,000.
The suspect ran away toward the East 14th Street and 1st Avenue subway station.
Anyone with information is asked to call the NYPD's Crime Stoppers Hotline at 1-800-577-TIPS (8477) or for Spanish, 1-888-57-PISTA (74782).
RELATED | Horrific attack on Brooklyn sidewalk by stranger leaves a woman in a coma
* Get Eyewitness News Delivered
* More Manhattan news
* Send us a news tip
* Download the abc7NY app for breaking news alerts
* Follow us on YouTube
Submit a News Tip