the ring is to be "flowy" but to sit snug on the ring surface as well..
"flowy" = T-Splines of course.. fitted.. well thats another story.. so I married old and new.
I brought some pictures of the ring into Rhino and scled them, then using a tsplines torus primitive I made a band, grabbed a few edgeloops and pushed and pulled till it looked about right.. remembering to leave it a touch wider for step2.
The lovely wife them milled the wax blank for me and time for step 2, which is basically melting the master ring into the wax pattern.. this is how I was taught to do it as an apprentice.
I placed the original ring down on a steel surface and lightly warm the metal.. heat here is critical.. too hot and you destroy the blank, to cold and it does not impress on the wax.
HEAT and PRESS!
carefully you seperate the two, too much force will break the wax, but hopefully you end up with a perfect pressfit :)
The proof of the pudding is in the eating so here is the finish article :)