Recently, there was some talk on our forum about making rings. I mentioned that I always use a head tweezers to secure the top of the ring to the shank, like with this orbit ring. This tweezers will work with any ring unless it has a large open area, bigger than the pad on the tweezers, like this ring. In that case, I used a piece of enameling sheet mica and used it as a support for the tweezers' pad and it worked just great. The mica provided a flat base that is simple to shape and heatproof.
I hope this makes your ring fabrication easier!!