Detectives say 37-year-old Linda Hernandez, of Islip, took the necklace from an 82-year-old man at North Shore University Hospital on July 5.
Authorities reportedly found the necklace, worth about $2,000, at a jewelry store in East Islip.
Hernandez was placed under arrest on Wednesday at 11:30 p.m. in Manhasset without incident.
She is charged with fourth-degree criminal possession of stolen property.
