I placed the cut rings flat on a piece of plastic or plastic surface and I put a drop of water in the center to fill the hole up like a miniature pool. The water seems to stay in the center and seep a bit underneath the ring as well. The water rehydrates the clay only where the water and the clay are in contact. I let it sit for a while so that the center gets soft again. The outer edge does not rehydrate, so that stays rigid. The plastic underneath helps it to stay wet while it sits.

Then I flip the ring over and the bottom becomes the top which then is a bit moist too which makes it easier to push a fire in place gem into the clay bezel. I test to see if it is moist enough by using a pointed shaper to push into the hole of the bezel.

If it gives well enough I know I can push the gem in until it is "seated" It comes out pretty clean and uniform, however if you don't let the inside rehydrate long enough, when you push the gem in the bezel, the bezel will crack.