I am wondering how to do this with FluidRay? We have been using Flamingo as our Renderer and this is how we structure our Rhino files so we can render different versions, materials.
Also, how does this model structure, same gems on multiple layers with different materials.
Probably the easiest way is to make 3 copies of the same peace of jewelry, assign the different materials on each copy, and then to switch between them, just connect the model of the jewelry version you want to visualize to the scene node. Something like this: