Cobalt chrome customizable ring core, polished top and polished comfort interior. 

Flat top with no inlay groove, perfect for ring makers wanting to customize the channel to any requirement. 2.3mm thick and 8mm total width comfort core interior

No need to make the core from scratch, all that's required is a channel and a little finishing afterwards and these become custom cores.  Unetched / heat treated as rings are easier to machine as such.

Sizes 5-13 available