On mine I spray them h a red oxide primer, then I apply the gold leaf fully to the inside and randomly on the outside. Next I dry brush the entire exterior of the cup with some acrylics that I mix. Afterwards I apply a mix of plater of paris, portland cement and sand that I've crushed very fine with a mortar and pestle, basically the same ingrediants used in ultracal 30, I just use a different ratio.
The original grails were primed in a red oxide color, cherry red paint applied, gold leaf applied sporadically on the outside, then had ultrcal 30 applied and they would then rub some off until the desired look was acheived.