+What color would you say Rarity's mane is? It looks dark purple but I have trouble with color.

I think it's a dark blue or indigo color.

4362583 yeah it looks indigo, thanks

4362567

It is the color of you're heart!

Everypony sees a different color; the color of there heart!

4362599 Whoa...thats deep.

4362567
The wiki has the answer.

4362567 royal purple

Make it easy on yourself and say purple.

It's obviously white and gold.

...what?

4362567 Deep violet. It's the sort of amethyst-ish, darker violet, colour that can only be achieved by gemstones or computer programming.

4362567

(Source)

Call me simple, but I just like to say purple and leave it at that.