Greetings I’ll take a stab at this one for you as 90% of the work I
do is bezel set opal, the remainder being pearl settings with the
occasional facetted stone job thrown in for good measure. The
question you’re asking seems to relate more to alloying metals
rather than making bezels, so I’ll answer that question.
To create a good alloy from scratch isn’t that hard. This is for
18ct yellow gold only, other rules apply for other golds.
Start with pure metals purchased from refiners. Don’t use old coins
for the copper as they are suspect as to purity. Use granulated pure
silver and gold. My favourite yellow gold alloy is 75% Au, 15% Ag
and 10% Cu, any more copper than that creates an alloy that is
pinkish and not as pleasant a yellow as I like.
Make small melts of no more than say 20 grams (approx 2/3 of an
ounce) of pure gold, plus the alloying metals. If you need larger
melts than that, alloy the gold in two or three lots and then melt
the three ingots together.
Wear the correct safety glasses. Using a Little Torch with an LPG
melting tip attached and Oxy, LPG as the gases, melt in a ceramic
crucible held in a holder of some kind.I use old bent up fire tongs
(real high tech stuff huh!).
The crucible should have already been heated and had borax melted
into the bowl. Preheat a metal mold for the gold to be poured into
and coat the metal mold with a light machine oil or baby oil. Don’t
use heavy oils as some have bad effects on the metal when it is
poured in. They can create a soot that causes cracking in the
gold.(Trust me I’ve done it and suffered)
Place some of the gold, all the silver and copper in the crucible
with a pinch of borax, melt together until no sign of the metals
remaining separate is visible. Do this by swilling the molten metal
gently around in the crucible, it should look smooth and fully
molten. Add the remaining gold and check again that the alloy is
fully molten. The metal should roll around the crucible and appear
like mercury in the way it flows.If there is any metal in the alloy
that hasn’t been fully melted it will show up as a lump in the
surface or you should be able to feel it through the handle of the
crucible holder as it rolls around in the bottom of the crucible.
Only practice will give you the right feel for this. Take your time
to get the alloy fully molten.
You don’t need to get the alloy up to the melting point of pure gold
to make it all melt. The silver will make the gold melt at a lower
temperature. Fine gold 1063 C 18ct yellow 927 C.
You said you had streaks in the gold alloy. If the streaks remain
shiny when the 18ct is annealed it is pure gold and your alloying
temperature wasn’t high enough or long enough. This may happen from
time to time and is no more than a lesson in progress, so that next
time you will be aware of the problem. You know what they say
"practice makes perfect" (Who are “they” anyway?
Remember that you shouldn’t anneal the resulting ingot before it has
been worked at least 50% smaller than it’s starting size or it may
crack. I call 18ct yellow a masochistic metal as it needs to be
abused to get the best out of it (no offence intended to the
masochists out there). This is for the first rolling only, after that
it doesn’t seem to make a lot of difference.
From there on make the bezel as you normally do.
Hope this is useful and happy alloying. Should you have any problems
you can contact me off line at @William_Nicholas_Rus
William Russell in humid Nth Qld Australia