Cops have collared a 46-year-old man who they say snatched a $900 chain off a 4-year-old boy over the weekend, The Post has learned.

Orlando Deuras was arrested Thursday and charged with robbery, police sources said.

Deuras allegedly went after the tot’s bling around 12 p.m. Saturday inside a building near West 182rd Street and Audubon Avenue in Washington Heights, cops said.

Police said the boy was visiting his grandma at the time and suffered a cut to his neck.