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Soldering Cubic Zirconium


#1

Can CZ be heated with a torch without damage? I recently set a 4mm
brilliant cut CZ in a sterling tube setting and then soldered the
tube setting onto a sterling silver pendant. After pickling, I was
polishing the final pendant and the CZ shattered? What did I do
wrong? I have soldered CZ before without any problems. The CZ I
used this time was of high quality (reputable mail order). During
the soldering operation, the CZ glowed red. Is this a problem ? Do
people normally solder CZ. Also, I did NOT quench the CZ in water, but
let it cool slowly.
Thanks
MILT


#2

ALL, CZ comes in many different qualities of base material. Cutting
factories buy their CZ rough from many different manufacturers. I
know of at least five different laboratories which make CZ. They
make it in many different clarities and colors. All these varieties
require different chemical formulas which effect the way the stone
reacts to different treatments. Your supplier has no way to tell
which formula was used to make the CZ they sell. Suppliers look at
the cut and clarity, not the chemical formula. As a stone cutter I see
many stones damaged beyond repair by torches. Everything from
diamonds, corundums, beryls, garnets, etc. Gemstones are all heat
sensitive. You may get away with torching stones for a while, but in
the end you will be at the cutters or stone suppliers buying a
replacement stone. The only 100% safe way to handle gemstones is to
not put a torch near them. That is including ring shank resizing.
Pull the stones and remount them. In today’s market that cannot be
done. That is why the large stone clearing houses sell so many cheap
stones. You will not take the time to pull a $5 garnet to solder.
You break it and call next day delivery for a $5 stone. $5 stones
are what are in most jewelry on the market because of the supply
houses which can quickly supply replacements from the sweat factories
in Asia. Our whole industry supports this. Every shop I go into has
a call in policy at the end of the day to be sure they get the
replacements the next day. The customer never knows his stone was
broken. Gemstones are precious. Please do not torch them.

Gerry Galarneau, Galarneau’s Gems


#3

Can CZ be heated with a torch without damage?

It’s iffy. While heat, on it’s own, won’t bother the C.Z. (consider
how they are made, after all), rapid heat change will, since the
material has a considerably higher thermal expansion rate than, say,
diamond. Sometimes, if you’re gentle, you get away with it just fine.
Other times, you don’t. Silver is harder on the stone than gold,
since it transmits heat so well, and can either heat or chill the
stone more than gold would.

   I recently set a 4mm brilliant cut CZ in a sterling tube setting
and then soldered the tube setting onto a sterling silver pendant. 
After pickling, I was polishing the final pendant and the CZ
shattered?  

Wait here. You say it shattered while you were polishing, or was it
just that you did not notice it until then? If it shatterend during
polishing, then the heating was not to blame. Except for one
possiblility that occurs to me. If, in heating, the silver expanded
enough that the C.Z. was then loose, the C.Z. might have moved and
jammed into a position not properly in it’s seat, and on cooling in
the silver, be left under considerable stress. Then, vibration of
polishing might do it.

   What did I do wrong?  I have soldered CZ before without any
problems.  The CZ I used this time was of high quality (reputable
mail order).  During the soldering operation, the CZ glowed red.  Is
this a problem ? 

Glowing red is a bit more than most of us risk with C.Z. In addition
to just breaking, you can also cloud over the surface of the stone if
it gets too hot.

 Do people normally solder CZ. Also, I did NOT quench the CZ in
water, but let it cool slowly. 

Cooling slowly is essential. As to whether most people solder CZ,
I’d guess the best answer would be “sometimes”. some people do it
with impunity, especially on commercially produced lines where it’s no
problem to scrap a broken one now and then. But in pieces where a
broken stone causes major hassels, then it’s preferred not to solder
the stuff. it’s not impervious to heat. Just sometimes able to
withstand soldering if done carefully and gently. Or to state it
another way, the stuff is dirt cheap. You can afford to take risks
with it. So when we need to risk it, we do.

Peter Rowe