YM 16628 bracelet discoloring

[Karlswe]

Hi,

I bought a YM 16628 in pristine condition some years ago. I wear it every now and then and the watch is in stellar condition with box and papers. I have however noticed some small discoloring in the polished part on one link, can someone tell me how this can happen and how I get rid off it?
It is barely noticeable at all and its very hard to capture on picture.
I attached two pictures.


Best regards
Karl

[BriansRolex]

Looks like a chemical stain of some sort not sure how to remove it without a polish but others might have more advice