I’m assuming you mean a faceted stone? If so below are a few photos
of how I was taught to set a faceted stone from behind and the "tabs"
as you can see are on the long ends of the bezel. Before the "tabs"
were bent over there was another bezel (frame) to fit behind the
stone (for security), then the “tabs” were bent over. I would think
you could cast your design, then make the frame, insert behind the
stone, then bend your “tabs”.