There is a fixture that's made of carbon in the shape of a ring
mandrel. I have one and I haven't used it in a while but I
remember that it took a lot of heat to get silver up to soldering
temp. I dunno how it works with gold.
just a comment on this, and other posts that mentioned these graphite
rods. The reason they can be hard to use is that graphite is an
exceptionally good conductor of heat, so the graphite drains the heat
away from the metal almost as fast as, say, an aluminum or silver
mandrel would do. That makes getting things hot enough to solder when
on one of these, sometimes quite difficult. But there’s another
option. In addition to these graphite mandrels, you can get the same
type of tool, a tapered heat resistant mandrel mounted on a holder
for soldering, but made of a ceramic material that’s NOT a good heat
conductor. These make it much easier to get the thing hot enough to
The graphite ones do have their uses, though. Sometimes you WANT to
keep most of the ring cool. With my graphite one, I modified it with
a flat surface filed onto the top, much as some grooved mandrels are
made in steel, though with mine it’s just a flat facet. That section
of ring over the flat is not in contact with the graphite, and it’s
possible to heat it up for soldering, while the sections in good
contact with the mandrell are kept cooler. With silver, of course,
the heat sinking capability of the mandrel is little bothered by the
flat, since the silver so easily moves the heat past the gap anyway.
But with gold, it can be useful.