A model of a D20 dice with a node tree to make different colors easy include a glass node / diffuse node on a mix node.
Also animated with the physics system. also UV unwrapped with seams. Includes a UV map
My video of Rolling D20:
Haha! Beauty of a job!
I agree, it's glorious!
I've used your d20 object and texture to generate 2d animation sequences for each of the d20 possible (20) results. Uploaded the set to opengameart.org.