As Jeff mentioned the fittings were not highly polished when new. During the manufacture process the fittings were chemically polished or brighten . If you don't have some well preserved NOS fittings to compare to then the next best example is what the highly polished brass dulls down to in a few weeks to a few months depending on conditions. I have purposely "patina-ed" brass fittings after polishing with acid based products like wire wheel cleaner. You have to play with it a little to get the desired effect. It is hard for me to describe in words the typical surface but I have samples to compare to so it is easier for me. Maybe someone else can articulate it better. It is duller then the highly polished level. Once I get to the desired level i will coat with T9 to help keep it from oxidizing further.