You do not note if the proposed enameling is via a kiln or torch
firing. If carried out in a kiln the profile of the ring is not
critical as the piece will heat relatively uniformly.
While others on the forum may well have other suggested techniques
and advice, the two main difficulties that I normally confront on
sterling are :-
a) Limited head room between the firing temperature of the enamel
and the melting point of sterling, on the ninomiya enamels I mostly
employ this is only around 40-60C and if your kiln thermocouple is
inaccurate then disaster can ensue.
b) The silver has to be “raised”, that is, heated to annealing
temperature and then pickled to oxidize the surface copper leaving a
fine silver film, typically I would do this between 3 - 6 times. The
fine silver film can be readily detected by eye as the piece will
slowly change from the sooty grey of sterling to the powdery white of
fine silver as the heating/ pickle cycle proceeds.
You need to exercise a degree of care during polishing post the
final pickle as the surface layer of fine silver raised is only
atomic diameters in depth and can be easily abraded away back to the
sterling layer during the polishing preparation.