Dial and movement look genuine but very dirty. However, Omega Swiss made cases generally do not have hallmarks on the outside. I’ve never seen a “0.720” hallmark (17.28K) either. Beware! gatorcpa
A thorough cleaning by a good watchmaker might improve the appearance of the movement. It is very difficult to determine if the dial can be improved or further damaged by cleaning. So I would say to leave the dial alone. gatorcpa
The dial probably would need to be refinished. This would hurt the value of the watch from an collector point of view. Mouvement can easily be cleaned and serviced.
Just noticed that seconds hand is broken and should be replaced. This watch is a dog with fleas. Run away. gatorcpa
Don't like that at all. As above. hallmark is wrong for 18K and shouldn't be on the outside. I have never seen a legit Omega like this, even one in a local case, which this may be. Somewhere that allows 17K to be marked as 18K for instance. That is a Swiss hammer makers mark but those are surely not Swiss marks. ps hammer mark 172 is for case maker Novelor, Jean-Pierre Dubois of La Chaux-de-Fonds in Switzerland. My money says it isn't from there...
The other watch the OP asked about was a cal. 266 and had a subseconds dial. https://omegaforums.net/threads/omega-caliber-266-fake-or-not-help.86521/ gatorcpa