I love pewter casting and I've worked to develop my own way of casting stones, into a pewter setting. I make a clay/sand mold for each individual stone, put the stone in place (hence the name ;) and pour molten pewter into the mold.

After that, there's lots of sanding, oxidizing and a few hours in a tumbler, then polishing. It's a bit of a process, but the result is beautiful! Since only the strongest of stones can withstand the high temperature, I also solder some stones to protect them from cracking.