If it is original then it does not have the look I value. I am not an expert, but I would want to see the plots less green, and more in keeping with the hands.
I think the dial is genuine, but probably a later replacement. The watch did have a lot of exposure to the elements, as can be seen by the bezel. However, the dial looks much fresher. There area also differences in the lume between the dial, hands and sweep hand. Its quite possible the dial and sweep were replaced at some point. Nothing wrong with that, but the watch is not exactly the way it left the Omega factory.
Shade of the hour markers don't seem to match hour and minute hands. Perhaps the hands are replacements or its a redial? Don't know ... Seems you should ask for a photo of the movement as well.
I would guess replacement dial, it may have been relumed but it has the obvoius dots in the 12 and 6 markers. I'm not sure if the replacement dials have these,