Our artifact was created using  a directional light pointing down the z 
axis towards us, intercepting first a fully transparent sphere (with a 
slighly smaller solid sphere in front to block some light).  In front of 
these two spheres are a series of other spheres in a double helix centered around the z 
axis toward the viewer.  By using a transparent sphere to block the 
directional light, and then a couple solid spheres to keep things from being too 
bright, all the illumination within the scene is a result of refraction 
off differently colored spheres.