A suspect in a robbery at a diamond district jeweler was arrested Monday, nearly a week after two men, one posing as a delivery man, pulled off a brazen daytime heist at gunpoint, police said.

The man, 37-year-old Rondu Frisby, was charged with robbery and various drug charges for allegedly letting another armed man into the 47th St. jewelry store. Frisby was awaiting arraignment on Tuesday and could not be reached for comment.

Frisby, an acquaintance of the store’s owner, helped pull off the heist, police said.

Police were also looking for a second man, identified as 58-year-old Leon Fenner, whom they said posed as a delivery man to get inside the eighth-floor Watch Standard Jewelry store at about 2:30 p.m. on Nov. 11.

Once inside, police said Fenner demanded four employees empty the safe. But when a fifth employee, a 56-year-old man, came in and interrupted the robbery, police said Fenner pistol-whipped him.

A third suspect stood guard outside the jewelry store during the robbery, police said.

Police released a video of two suspects a day after the violent attack shut down a busy stretch of the diamond district. In the video, the two men are seen separately, pacing in front of the stores along the well-trafficked street, apparently before the robbery.

Frisby was not one of the men on the video, police said.

Officers shut down the block and canvassed the area immediately after the heist. Investigators also pulled surveillance video from inside the building, police said, which was just off the route of the Veterans Day Parade.