Jeff and Abel,

I would not imagine that these watches will corrode along the years like a rusted piece of iron...

In metallurgy we use the term "Passivation" when the surface of a metal creates a very thin inert surface layer,
when in contact with environment, that inhibits the deep corrosion of the metal itself.
It is a layer of very few nanometers so there is virtually no loss of material in this natural process.

I would add that in past auction of other brands, these "passive layers" added a huge premium to gold watches auctioneed,
because it witnesses that the watch has not been worn for ages!

My opinion? I would never remove it!!