Hmmm the seperation is to difined for my liking, it doesn't have the feel of light emanating through paper.

 Dithering like it is shown here PJTUT would be good c:

 Thanks for the advice =)

The colors are pretty!  Maybe some touches of purple in daker areas give a special effect to it.
The dithering is nice, but could be done better.  This way the colors don't blend in each other very well. Every pixel placed wrong when dithering destroys the dithering-effect, take care of that.
And some AA would be good -  you used it on the left round part a bit, but the rest needs it as well ;)