80's Omega Seamaster Quartz info

I own an Omega Seamaster Quartz that I believe was purchased in the early 1980's in Europe. I took it to an Omega dealer and they didn't provide much info as there are not a lot of markings on the watch and it did not appear in the large Omega book/catalog that shows watches going back quite some time in history. I believe it is 18K gold. It is on the smaller side, maybe 36mm, and the dealer said they cannot find any additional links to make it larger (it's tight on my wrist). Wondering what this should be valued at in a sale or trade, and any other info on it including dating, model numbers etc. I did some searches on Ebay and the net and don't really see much out there that matches this watch. It has never been serviced and I do not have any of the original papers or the original box.

The early 80s were Omega's darkest hour and watches from that period are mostly forgotten...having said that they should still have a model number inside the case, didn't the dealer open it?
You could try looking for it in the catalogs available on old-omegas.
It's unlikely to be solid gold but if it is there will be obvious hallmarks on the case and bracelet.

The dealer did not open the case. What sorts of hallmarks should I look for to determine if it’s solid gold?

Does the claps has a coding inside? Often its possible to determine a model by this, if you have no chance to look onto the case backs inside markings. In your pictures it seems, that there are no codes in the claps ?- wich is very unusual....anyhow may be I cant see the code? We have not seen this reference before. For me the case back does not look like OMEGA with these fluted edge. Also the hands dont look OMEGA-like. So it would be utmost important to see a picture of the movement and case back inside to confirm its a OMEGA model as such. Kind regards