How to generate a prism effect

[erhew]

Hi all, I'm new to using V-Ray, but I'm trying to render a scene that has a series of broken mirrors adjacent to prisms. I've gotten the mirror material working fine, and the prism material is somewhat working, although it seems to be rather finicky.

I am looking for the light to pass through the prism and onto the ground, as well as for it to produce the rainbow effect, like in the picture I've attached. However, so far no luck. As you can see in the renderings I've attached, the rainbow colors seem to stay on the prism. Does anyone have any suggestions on how to proceed?

[erhew]

Update: I've been playing more with settings, and I've gotten the colors inside the prisms to be more reliable. However, I still can't seem to get any sort of light cast onto the ground, colored or not. What I am looking for is something along the lines of the pretzel photo I've attached, but my prisms don't seem to be casting any light at all. I have caustics turned on and I'm using vray sun for the lighting.

[Grigio18]

Use only one light for caustics, aa spot light is simpler, do not use dome or sun light.

Follow this tutorial..

https://youtu.be/cgeRmP9CUZI