Hmmm. If we look at a totally "new" Parker (or other gun - think Muederlak's Trojan") we are looking at a set of colors which are about 100 years old. How do we know what the colors looked like 100 years ago? Not that it matters, but is it possible that colors change over 100 years?
Yes, certainly. Especially the vividness of the colors. I'd speculate that once the lacquer or other coating wore off the brightness would start to deteriorate. In discussions with other members, I've made the point that you also have to consider the tastes of the Victorian and Edwardian periods, which were oriented towards bright primary colors and very eclectic mixes. My family has a history of restoration of Victorian antiques. Once I walked into the "Renaissance Revival" room of the Met, and it was like walking into my parent's house. I hypothesize the colors were very vivid at the time, as well as providing a complement for the high contrast of the Damascus and Twist patterns of the tubes. I recall a painting I saw set during WWI, which showed an artillery crew painting their gun like a huge Damascus tube, with very bright and eclectic colors.
I suspect the colors of the guns were spectacular when new, essentially what I call "Party Favor" guns. Too bad it was before color photography.
