Watched this film many years ago. It was about a forgery of a charcoal drawing I believe. The artist needed to recreate a famous charcoal portrait of a woman but had to do the forgery in a very short amount of time and from memory in order to make the switch with the original. The artist practiced over and over drawing the portrait but when it came time to do the job they forgot to draw the jewelry (earrings or necklace I believe) the sketch was then examined by experts and they determined it to be authentic because history said that the subject of the portrait had received the jewelry as a gift after the portrait was done. This meant any portrait depicting the jewelry was actually a forgery. So the artists mistake ended up being their salvation.