Depends on how sure you want to be. On an Omega you can order an extract and be sure. You can use serial number charts which may or may not be right... err exact.
Seiko is pretty easy as the serial encodes production month and year.
Some periods of Rolex are very exact.
@Maganator - so you just bought that Seiko now?
A "birthday watch" popped up a year or so. Yes a birthday not birthyear watch since the Extract clearly stated production date so. An original speedmaster moonphase 345.0809. However I was just into watch, had no gut and fund for a 10k euro watch.😟😟
A "birthday watch" popped up a year or so. Yes a birthday not birthyear watch since the Extract clearly stated production date so. An original speedmaster moonphase 345.0809. However I was just into watch, had no gut and fund for a 10k euro watch.😟😟
I've never enjoyed looking at papers, I'll just take the watch 😗