Hello, all. I have been trying to render some gemstones, Emeralds in particular, but I can’t seem to get Blender to make them sparkle.

I have all the data I need for gems: IOR, Brewster’s Angle, Critical Angles, Color Filtration, etc, but I don’t know how to convert these numbers into things Blender can use.

An example is this: My emerald has a Brewster’s Angle of about 57.60415 and a Critical Angle of 38.68-39.56.

I know these effect fresnel and that Blender’s Fresnel slider goes from 0 to 5, but what does that mean in angles? How would I achieve the effect of a certain critical angle or Fresnel for certain gems?

Blender’s not really good on caustics, you might want to try a different renderer;
Luxrender, Indigo, Yaf(a)ray, Yafray.

Or have a look here:-