Super, you are on the money with purple/mauve as you are about the night time change as well. The most dramatic is when the sky is a bit overcast. It looks like paltinum on top and fades to black at the bottom. I just have a hard time telling someone who has not the seen the car in person what color it actually is.
911driver, I asked the same thing when thinking of replacing te Turbo tail with a Carrera (84+) or Weissach style tail. Take a look at this post and look for the sketch from Pano. This might help. The most important I've seen over and over is that one (chin/tail) doesn't work well without the other.
http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=1&t=002673
Tony