There is a (very expensive) color used rarely by Ford and made by BASF called "Mystic". It is no color and all colors - LOL. What I mean is that it changes based upon where you stand when you look at the car, the sunlight, etc., The vehicle will literally change colors constantly.
Here is an article about Mystic, I will try to find a picture of a car with it....looks kind of shiny, dark, emerald green usually in photographs though.
http://web2.iadfw.net/robmu/colors.html