I sometimes buy an old watch and am not sure exactly how old it is. For most brands, the information is not so easy to find but for some brands like Omega and Rolex, the Calibre, Case and / or movement number will give you a pretty accurate indication.
For example my friend Andrew has this nice looking, Automatic, Omega Seamaster. He was wondering aloud the other day how old it was. This of course made me want to find out!
Based on the Calibre No – 1010 and the Serial No – 412XXXXX, you can tell the watch was probably manufactured in 1978 and is about 33 years old.
The following list, although not exhaustive, should help date your watch if you are interested.