Frankenwatch

A frankenwatch is a watch assembled from parts of different watches, sometimes mixing genuine components from several pieces, and sometimes combining genuine and aftermarket parts, so that the result doesn't match any watch the maker produced.

They're most common in vintage and entry-level collectible markets, and they can look convincing at a glance. The problem for a dealer is that the watch is worth far less than the reference it appears to be, and selling it as original is a serious misrepresentation.

Check that the movement, case, dial, and hands are consistent with the reference and with each other, and use specialist help for any vintage piece you aren't sure of.