How does customising a watch affect its resale value?

There are limitations when it comes to selling a third-party personalised watch at an auction
A question that arises, though perhaps only for a certain few, is the resale value of a customised watch. How much is a customised watch worth? It depends on who you ask.
Personalised watches are, as the name suggests, personal in nature. Here, it is sentimentality, not the value of a material or the cost of labour, that matters.
“We are [constantly] monitoring the [second-hand] market and the first surprise for me was that people don’t actually resell their [Blaken] watches because [they buy it] for sentimental value [not as an investment piece],” says Klingbeil.
And if you are thinking of going down the auction house path, be aware of limitations.
“With regards to third-party adaptations – there is a market for it, definitely, [however] we try not to encourage people to go down that road, because manufacturers haven’t really justified that [third-party customisation] should happen to their watches,” says Tim Bourne, Bonham’s international director of watches, Asia.
Much of that has to do with the fact that it is difficult for auction houses to rely on manufacturers to authenticate the timepiece.
“They, in many cases, will not provide that documentation if they know the watch has been played with in some way,” says Bourne.
But if you are eager to personalise your watch to your taste without killing your chances of potentially selling it at an auction, consider the “safer” customisation option: changing the straps.
“This, in some ways, is what we would describe as a nice customisation, an approved customisation,” says Bourne. “Once you start messing around with the dials and things like that, it’s far more tricky.”