Rub-over cabochon help

[LapisLazuli]

Hi Experts,

I hope you can see the attachment? It shows a rub over ring blank with an open back, and a stone that fits pretty well inside it. The stone does not sit flush, it's a couple of mm proud. I bought these from Cookson a while ago as a "fun" personal project but I'm having a bit of trouble getting it to work.



I've annealed the ring twice and just can't get the metal to budge at all around the stone. I can see very tiny spaces where I've been trying to push the metal towards the stone. I'm using a notched pusher as I read that these were more effective for this kind of thing.

It obviously needs to be a snug fit but I can't see how.

Do you have any suggestions? At the moment it's solid and I'm not getting anywhere with it.

Should I be glueing the stone first or something? I've used bezels with limited success before but this is quite different.

Any help would be appreciated!