Brushed buckle question

[Tan]

All,

I have a PAM 112 and the watch came with a brushed buckle as opposed to a polished buckle. This is a K serial so quite old...my question is was this a choice that the original buyer could choose from upon purchase or swapped from polished after the fact? I've seen some photos with polished buckles and some with brushed buckles so I'm not sure if this was an option at purchase or something done by folks after the fact.

Thanks!