Hi, everyone I have a nice vintage Zenith square tank 18k gold watch maybe from 40's. size is 24.4mm without crown. If someone know about this watch, please let me know what kind of metal being used on this movement case. I found the case back marked 18k (0.750) on the case back and case also 18k but not too sure if the movement also gold as looks really shine pristine and rust free from maybe 80 years old watch.
So my question are how old is the watch and what is the metal on the movement case?
Thank you so much and your help will be really appreciated.