Oh, I can explain why I chose to pixel this...
y'know, I was listening to Pink Floyd, and had this Circle Template looking at me on MS Paint... There you have it!
7 colors, including the back of the circle.
P.S.: The borders are not transparent, they are just the same color as the PJ page. I only have MS Paint here, so I can't rely on the alpha channel. I hope it will be accepted on the challenge.
[EDIT] The background is now transparent. Thanks Skamocore!