rarity! fuck yeah! i agree whit Stashabobasha, though i can see that doing it whit purples may make it look odd, being rarity and all that, and using 2 colors would broke the idea of this set of pics :/
Thanks for you're feed back, I gave this some though myself.
I originally planned to do this one purple but it was really close to Twilight's colors. Also the other 5 wallpapers use a color close to the ponies skin tone, so i didn't want to use purple for Rarity.
So it needed to be white to fit the style, but that's impossible without contrast so the similar color to white is gray. I didn't like just gray tones though so if you notice (maybe take a color dropper in an image editor) its not gray; its blue-gray. This blue-gray made a huge difference to the image IMO.