Think of soldering gold bezels to silver as similiar to soldering
silver bezels to silver. I would use a hard gold solder for the seam
of your bezel and then a medium silver solder to attach the gold bezel
to the silver. If the silver piece is much larger and heavier than the
bezel then you need to make sure that you have warmed the whole piece
before concentrating your heat around the area that the bezel is on.
Sometimes I will heat from the back, underneath the area the bezel is
on, to help bring the metal up to temperature before heating from the
top. Keep the torch moving around the bezel until the solder starts to
Gold if it gets too hot or is heated too fast will sometimes oxidize
before the solder flows, if this happens usually it doesn’t matter
how much heat you put to it the solder won’t flow properly and things
tend to start melting at this point. When this happens the best thing
is to pickle the piece and clean with a white 3M scratch pad, or
whatever you use, before trying to solder again.
It just takes a little experience to know the visual cues of when you
are getting close to the flow temperature of the solder and when you
have applied too much heat or for too long and you need to start over.
Hope this helps.