Learn how to achieve a caustics effect using a node shader.
Matthew Heimlich writes:
Just completed a video description of a material that will allow fast fake caustics in Cycles. It's especially useful for those interested in having a caustic effect that looks visually pleasing but aren't so interested in the super long render times required for true caustics in a path tracer. Anyway, hopefully it can be of some use to someone out there. Hope you all enjoy!