The case shape does remind me of the nationally-cased bumper automatics sold in the US during the 50s, so I'm personally not yet convinced it's a fake.
The most we can say from that photo is that the dial is not original from the Omega factory. Best case scenario it is an authentic Omega watch with a repainted dial. Worst case scenario is that the watch is a knock-off. More photos from other angles, including of the inside, will tell the story.