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Casting CZs in place


#1

Not a gemologist here…but I’ve cast quite a few CZs in
place…some in gold, but most in silver. The manufacturer is going
to warn you about the size of the stone being the problem with
fracture, but I’ve found ways to temper this a tad.

To start with, remember that it’s heatshock that’s going to ruin
your stone, not necessarily just high heat. CZs, being created, lack
natural fractures and such like real gems, so are not going to be
prone to easy fracture in this manner anyway…likewise there are
several colored synthetics out there that you can cast in place as
well. (On a similar note, there are several colored synthetics out
there that can NOT be cast in place too…it has to do w/ the
crystalline structure of the synthetic or something…that will take
a gemologist to explain)

To help temper heat shock of your synthetic stone, simply burn out
your pattern at a higher temp than you normally would, keeping in
mind the tolerance of your investment material. I routinely use only
high heat investment, and that way I can always heat it up pretty
much as high as I want…just don’t get too close to the melting
point of your metal either.

In this manner I’ve cast quite a number of 10x12 emerald cut CZs in
silver. I’ve only ever lost one to fracture, and it actually wasn’t a
complete loss(I was playing anyway). It was a 10x8 oval CZ cast in
gold, and I got distracted with a patient(wish I could eliminate
them…heh), and I cast w/ my metal too hot.

As a side note…when I cast in place, I generally to a bezel type
mounting…metal all the way around the girdle. That may make a
difference.

David A. Cowling, DDS PA
GENERAL DENTISTRY
222 East Highland
Malvern, AR 72104