[Looking for] Ring mount supplier

Hi, I’m a novice stone setter and I’m looking for a supplier of ring
mounts. I need something that can accomodate stone that are, say,
5mm in depth, flush or pave set into it. Base metal versions of these
monuts would be emmensely helpful for practicing. This might seem
like an obscure request but most of the rings from Rio Grande/etc are
way to shallow to accomodate the stone I want to set. thank you. -Tato