This is a shot I took a couple months ago for a training video I was shooting. I thought shooting the black dress on the black background would have a lot of impact. The key when shooting a black object on a black background is to create separation from the background. The best way to create separation from the background is creating highlights on the black dress. This was accomplished by placing two edge lights behind the model at a 45 degree angle. See lighting diagram below.
Main light – 4′ x 6′ softbox
Fill – 4′ x 6′ silver reflector
Edge lights – 1′ x 4′ soft box