Often dials that got water-damaged - which happened a lot - were repainted. I think yours is original but in that condition it's hard to be sure.
To be brutally honest, the watch is not worth spending money on. Original or not, the dial is shot, there is severe loss to the gold cap, odds on the movement is in bad shape and the crown is wrong (they all had the Omega symbol at this date). If it works, best to just wear it as is and enjoy it while you decide whether you want one in better condition. The problem with cheap vintage watches is they are not any cheaper to service than expensive ones and frequently cost a lot more, so what seemed like a gift at first can become a liability. You would be lucky to get away with less than £150 for servicing an automatic like this by a competent vintage specialist, and that's for one without the issues yours has.
On the bright side, it is a real vintage Omega Seamaster. I would say from about 1958-1962 going by the S in Seamaster.
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