Vineland Police released surveillance video showing the robbers with guns drawn, running up to the owner as he closed up shop Friday.
They forced him inside Dondero Diamonds and Fine Jewelry on Delsea Drive and went from counter to counter. But the owner says the crooks mostly took inexpensive display items.
A police officer interrupted the holdup by coming in an unlocked back door.
Unsure if the suspects were still inside, SWAT teams were called in and held in standoff for hours, but the robbers had apparently fled.