I shown a spot light through a crystal with a marble wall ready to catch
the light. I got this image after about 6 hours of render time.

The rainbows finally came up. And somehow the Star of David appears
as well. Since this is actually what light is suppose to do when you
use a piece of glass shaped like an Icosahedron you can bet that with the
proper shape you can make a real version of it. Just saying... that if any
Jewish jewelers want to make an interesting art piece consider learning
about Icosahedra

Note how much clearer the picture is from this early render. Right away I
could see this was a promising image to continue with. So I let it run.

Still it's a mess. The idea to use a crystal like that came to me when
I was thinking about the glass kitchen crystals granny used to have.
And it dawned on me that I could just model a crystal like that and
use it. (One of those angles had to be right.)