Factory Chrome Vavle Covers on Litle Red 360

Since they were chrome instead of painted what color were the plasic spark plug dividers that snap into the covers?
Plain unfinished or where they shot engine color.
I was wondering since would have been on a painted cover. And painted when cover was.
I guess that the same would have been for late 60,s 383 thzt had chrome plated as well

So what were the plastics like