Dating longines watches by serial number
Not all vintage watches can be dated using the serial number.
Some American watch brands did not use a consistent series of serial numbers, but most of the big manufacturers did.
Wittnauer self-winding watches will have the word “automatic” printed above the 6 or under the Wittnauer name at the top of the dial.Vintage Wittnauer case backs can be removed to identify the movement and the engravings inside the case back.Vintage models either have a snap-down or screw-down case back.The inside of the case back should have “Longines Wittnauer Watch Co.” engraved on it. Obtaining the serial number list on post-1994 Wittnauers may be more difficult and may require contacting a retail Wittnauer watch dealer.
It's not recommended that novice collectors open case backs on contemporary watches.Snap-down versions can be pried open with a watchmaker’s case blade.