I'm guessing that's not a Lady's Rolex. Looks like a half hunter pocket watch that has had those lug bars added at some point to enable it to take a strap and be worn on the wrist. The serial number and silver hallmarks should help you date the watch, but if I was to take a punt early 1920s would be my guess, if not a little before.
Nice item, you should get it serviced and sympathetically restored.