glad you like the update, we are very proud of it 
the new DOF setup is just killer... what you hoped and dreamed of, no?!Like these dark dice very much! good stuff!
yes, what Frederik said, that dice normally are not made from glass, but from some sort of epoxy or plastic material, so an IOR closer to that of plastic than that of glass may 'do something' for you... may not.
I remember Notareal worried one time about the IOR for different TEMPERATURES of water- so... clearly it's important to some
folks. I probably would not know the difference, myself, 
but as I almost exclusively render architectural-type environments/scenes, my expertise is weighted in that direction. 
