i did this in a hurry it might not be the best i will reupload a new proper one once i get some time
1. makes sure mental ray is on, under indirect lighting tab turn on caustic
2. make a blinn material and make it transparency, go to raytrace option and turn on refractions. set refraction to 1.333
3. create a spotlight and go under mental ray> caustic and GI and turn on emit photons.
4. to control your caustic increase your caustic photons to above 1,000,000. yes that's a million
1. makes sure mental ray is on, under indirect lighting tab turn on caustic
2. make a blinn material and make it transparency, go to raytrace option and turn on refractions. set refraction to 1.333
3. create a spotlight and go under mental ray> caustic and GI and turn on emit photons.
4. to control your caustic increase your caustic photons to above 1,000,000. yes that's a million
