Brilliant!

Here's a sample. I used the Threshold shader as the parent to Fake Fresnel so you can get a sharp cutoff between the black and blue, no need to fool with the lighting. If you wanted something more gradual, you could use the Curve Filter.

Regards,
Eric Winemiller
Digital Carvers Guild
Carrara plug-ins

Eric Winemiller
Digital Carvers Guild
Carrara and LightWave plug-ins