Picked up this watch, which I believe is Swiss, and has a case that reads “fine silver.” My understanding is that this notation on a case means it predates the 1880 law that standardized Swiss hallmarking. The key wind also indicates it might be older. The case has a 4 digit serial number, but the mechanism has no number. Does anyone recognize the shield symbol on the outside of the case? Any help with figuring out more about this watch would be greatly appreciated. Thanks!