I took a few hours of break from school work to have some fun in Max.
I cooked up a shader that reflects rainbow colors on surfaces that are facing away from lights, with a falloff Fresnel gradient to control at what angle the iridescence starts. It turns out to be a much cheaper solution to compute than the triple anisotropic shader I had going on before. It gives me full control over the colors, where they are and how they interact with the lighting, while cutting render time 4 to 5 times. Win win!
I'm trying to approximate this : http://25.media.tumblr.com/tumblr_m.....d3g9o1_500.jpg
Not sure I quite got it yet..
Low res made in 3ds Max
Sculpting in Zbrush 4
Rendered in Max using Mental Ray, MIB_Blackbody shaders on skyportals for lights, AO + Diffuse + Iridescence pass
Assembled in photoshop