Today was better. I was able to fix the one bezel from yesterday even though it has a slight curve where I filed the seam smooth, and I set that stone. That’s today’s picture.
I started completely over with the oval bezel for the opal. Cut a new strip of silver, got it to the right size, soldered it closed, sanded down the edges, refitted it to the stone for the correct shape, & soldered it successfully – no gaps!! – to the back. Which was also newly created.
Practice and commitment. Tomorrow I might even get the whole thing put together.