I have made an example of “Diamond”.
Diamond has very high “refractive index” and “dispersion”, so it reflects light rays well, and makes fire from inside light rays.
However, current CINEMA 4D does not have the “dispersion” function (even R13 does not). Also there is basic limitation to simulate the dispersion in 3DCG softwares which uses simple “RGB” color model, if you use other renderers which support the dispersion, you can not get good result.
So I took very simple solution that “render many pictures, and composite them”. Fortunately, CINEMA 4D has “Scene Motion Blur (SMB)” which composites many pictures automatically, so you do not need to do this by your hand.
The dispersion is very simple idea that “the refractive index varies by color (wave length)”. So only you need to do in CINEMA 4D is animate color of lights (or luminated materials) and refractive index to corresponding values.
Additionally to automate this process with SMB, you need to complete one cycle of animations in just 1 frame. Then I desided to use “9 times SMB” first, and changed frame rate of the scene to “270 fps (30*9)”
Next, I recorded keys of “color” and “refractive index” from 0 to 9 frames, and set the track to “cyclic”.
That is all, when you render this scene, 9 pictures are rendered in 1 frame and they are composited to 1 picture. You may be understand the process easily by redering the sample scene
http://www2.11moon.com/sample_files/20111023/diamond_23.mp4
http://www2.11moon.com/sample_files/20111023/diamond_23.zip
