After enlarging the hole in the smoky quarts crystal I put a 1mm copper wire through, I then flatten the wire on both sides of the stone before wrapping it.
I attach oxidized sterling silver chain to each side of the stone and add a handmade copper s-lock, I give both the lock and the copper around the stone a rustic antiqued finish by oxidizing and brushing it.
Since the stones are natural they are a bit irregular in shape but they measure approx 20-25mm. The chain measure 160mm on each side of the stone and the lock approx. 20mm.