In skyring, black isn't used as an attractive colour. It is used to help create something dark to look into, as this makes seeing ecto-plasm, and different visions much easier. As you advance and open your phsychic centers, you're able to do the same thing whilst looking at anything.
The same method can be achieved by looking into a dark or 'pitch black' room, or into a dark bowl of water. It is about the darkness, helping to manifest the visions. Not a fancy colour to add effect.
-En Haradren Amlug.
