Watches such as the Rolex Submariner and GMT-Master have bezels to help a diver track time underwater or a pilot monitor 24-hour time in another time zone. Given that the aluminium bezel inserts would often fade or scratch in time, it is common for Rolex to replace them during service. However, originality is important to collectors, and in some cases, a 1950s Submariner, which original bezel insert can be worth tens of thousands.
Know that the movement in such a watch can also become so damaged from water and rust that watchmakers have to replace the whole thing. For brands where there is an extract (or certificate of authentication) from the archives, such as Patek Philippe, a movement with a serial number that doesn’t match the one on the case will make the watch harder to sell.
Polishing it only makes it worse
Look out for polishing, too. Some watchmakers polish old cases to make them look shiny and new, though most collectors prefer to retain the authentic, aged look.
Beyond aesthetics, another downside is that the process removes metal from the cases and causes them to lose the beautiful edges many had at the time of production, such as the chamfered edges that Rolex Submariners and GMT-Masters had in the 1950s and 1960s. The more polished a piece is, the less it is worth.
Eric Wind runs Wind Vintage, a watch shop and advisor to vintage watch collectors