Nathaniel Borgelt, horological coordinator at Patrizzi & Co. auction house, feeds you the questions you need to gauge a vintage watch's worthiness.

Is it signed?
The case, crown, dial, and movement should bear the company logo. Replacements lower the value, though a new crown is the least concerning.

Was the dial fixed?
Even if it's original, sellers may reapply the luminescent substance to the markers to make it look better. That drops the value.

Was the case polished?
Bad. Too much polishing removes and weakens metal.

Does the watch have provenance?
Engravings that hint at a watch's use (particularly military) or an interesting backstory make any watch more valuable.

Does it have any original accessories?
Ideally it comes with the box, papers, and service records – but it's rare to get all three.