Dramatic video released by the NYPD on Monday shows the moment a dapper robber pulled out a pistol during a $4 million heist in a Diamond District jewelry store that’s a favorite of rappers — and gang members, police sources said.

The bandit, clad in a stylish blue suit and wearing a gray fedora over long, thick braids, was seated at a desk in the rear of Avianne & Co. Jewelers when he reached down between his legs, surveillance video shows.

He then raised a silver-colored semiautomatic handgun and racked the slide, standing as he pointed the weapon at a worker on the other side of the desk.

Another video segment shows the bandit forcing a man to his knees in the back room, where bottles of bubbly and booze are displayed on shelves and a bar cart is parked in a corner.

Video also shows the robber’s two accomplices, one of whom also brandished a pistol and had long braids under a bandanna — with a police source saying both men appeared to be wearing