Does anyone know if the the Ademars Piguet, (AP), watch company used to number their watches? I have an old pocket watch my grandmother gave me, but at the time I was too young to think about asking the history of the watch! It has "AP" stamped on it, inside the back cover which opens so that you can wind it with a little "key". The number it shows is: 23917. I would like to get an idea of how old this is so that I will at least know if it could possibly have been my G-Grandfathers!