Susan,
It all depends on so many variables such as the shape of the piece
and the amount firings. It’s frustrating to answer, because the
question in some ways is like asking the question how long is a piece
of string?
My guess would be to start with 22 gauge and see what happens.
It is possible to skip the counter enameling of a small piece
jewelry provided the metal is thick enougjh----at least l8 gauge for
a piece no larger than l" square, and provided the enamel is not
applied in a thick coat. Having said that, I want to add that to
be on the safe side it is much better to counter enamel your pieces.
Why risk problems of cracking and warping?? If the back of the
piece is to be exposed, this is a great opportunity for you to do
something creative with your enamel on the back of the piece as
well as on the front. I set all my enameled jewelry in bezels,
usually use l8 guage fine silver,—sometimes copper covered with
gold or silver foil, and always counter enamel. Good luck, Alma