I buy sterling silver tubing and the flat bottom stones from Rio Grande. I use a micro lathe to turn a piece of mild steel with a recess area for the tubing to slightly press fit over. Drill and tap for the screw size. Silver solder the tubing leaving it a little long, set the stone and grind the tubing close to the stone. Carefully roll the edge over the edge of the stone to hold it in. Clean excess solder off by turning it on the lathe again. You can reshape the mild steel at this time too. Remove and grind to desired height. Buff and polish, blue the steel and youre ready to put it on. I see why jewelers get paid well.