"Why is it better to buy a used watch that is unpolished and how can you tell if it is unpolished? Thank you.
Thanks for the question.
You've obviously heard or read about how a polished watch is a bad thing. Of course this kind of goes against our natural reaction. Almost everything else out there is better when polished: cars, shoes, pianos, etc., but with watches its the opposite.
The main issue with polishing is that the process (often done with a polishing machine and some kind of compound), will not only remove the original intended finish, but it can actually remove material, and therefore certain details that are part of the case design.
For example, in 1966 Omega had some Speedmaster cases made by a company other than the usual company they used. These case were marked in the inside of the case-back with a "CB", which stands for Le Centrale Boites (the other company they used was Huguenin Frères). These cases had a kind of bevel or facet in the lugs and were a little more flat in certain areas. If you look closely, you would see a vertical facet as the lugs curve down inward.
This is a fairly important detail as it can confirm the watch really is a CB case, and as such, people will pay a small premium for those more "rare" cases. But, if the cases are polished too much, that detail will easily be polished away.
Other times in order to polish a case the case is actually sanded before the machine polishing. You can do a quick search in YouTube and you will see many examples of this. Of course now, removing a lot of material has consequences. Its not uncommon to see an overly polished case have one lug longer than the other.
Other details that can get polished away is the chamfer on the lugs of many watches. Rolex cases have such chamfers. If they are polished away, the lugs become rounded and lose that sharp slanted edge. Not to mention that trying to replicate the original finish or texture (brushed, etc.), is really really hard. So, the best thing to do is not polish anything.
Of course, this is not to be mistaken with cleaning or hand wiping the case.
When you service a watch, you most definitely want it cleaned. A watchmaker will disassemble a watch and with warm water and a cloth wipe it clean. Sometimes they will clean a watch with an ultrasonic machine, which uses ultrasound and just water to clean the case (or a gentle and appropriate solvent).
You, yourself can use a Cape Cod cloth (which we will post for sale soon, by the way), to maintain it's cleanliness. But, even then you don't want to overdue it too much.
I think one of the reasons why so many people do in fact polish watches is to remove nicks in the case or scratches. If the scratches are light, using the Cape Cod cloth manually can lessen it, but scratches and nicks are not things to worry about. The general rule is its better to have a scratch or a nick than an over polished case.
Over polishing literally wipes away part of its value and history.
So, keep your watches clean, but don't over polish them.