Fully modeled CD, with actual refraction on its back with the colors changing with the camera angle, i fiddled around the compositor to get the effect, it may not be perfect and so i'm open to any suggestion to improve it. For example, to limit the colors, I've used a color ramp with three sliders RGB, but, for some reason, the material itself does not use the entire spectrum, only colors from, say, Green to Blue without going from Green to Red.
Other than that, cover is already UV unwrapped, just replace the texture with your own.
Hope you like it.
Rendered at 1.000 Samples.