Thanks for replying. The downside of such effects in unbiased renderers is additional render time but I've seen some great looking jewellry images which use the same sort of material.

For a good test of Maxwell light dispersion, I tried rendering a prism scene ages ago but my old pentium 4 system couldn't really cope. Earlier in the year I assembled a new quad core system so I've come back to the prism test again.

This is a simple scene converted from a .dxf scene downloaded via the Maxwell forums. The light source is probably one of the most important things with this type of render. Inside the 'light gun' body is a long black diffuse cube, the front end is deleted and the rear end is split from the cube and asigned a Maxwell emitter material. This simulates a nice stream of light without much speading.

The prisms are just 3 sided Cinema cylinders. The body of the prisms uses a Maxwell 'glass' with an refraction value of 1.850 with dispersion activated. The prism end caps use the same material but with roughness used. This is how some of educational usage prisms are constructed.

There is an overhead light being used just to light the scene a little.