Grandfathers Omega....Regina?

Hello everyone. My grandfathers watch has been stored away since his passing in the 50’s. Unsure of origin, but he was based in Invercargill NZ.

From what I have found so far it looks closest to a Regina style but does not have numbers on the outside back. Have not taken it to a jewellers yet to open up the back. It’s my mothers watch and she is curious as to value. Not selling as has sentimental value. Is it wise to be serviced to see if it goes or just let it be?
Thanks all help is appreciated

Thanks so much Jim, we will take it to a good jeweller and see what the numbers are. The Regina was the only one I could find with a similar face, youve filled in the gaps thanks regarding not having model names. Mum seems to recall it being stored in a drawer and granddad having it repaired so that may explain the hands. Any idea on value without knowing the digits inside the case? Am I correct in assuming the back is brass? Thanks so much for your insight, appreciated.

For reference, your dial and hands likely looked a lot like this. I had this watch relumed by Everest Watch Works.