Here is another reprint from PMWest's page at
Once again, thanks to
Marc and the crew and hopes that he doesn't mind...
Stone In Casting concepts.......
1. Things you need to know
This is a more exacting casting process that differs only
slightly from traditional casting/finishing.
A. You must plan to sprue for a low flask temperature at
casting. See chart below. Use a dark strong wax.
B. You must exactly match stone size to the wax model being set.
Sieve your stones.
C. You need 70% new metal in each cast. This metal needs as low
a flow temp as practical.
D. You slow cool the flask at least 1 hour to "hand cool" temp.,
then blast off investment with a pressure washer. Do this in a
enclosed cabinet to recover stones that come loose.
E. You must tumble finish instead of stripping/pickling.
F. After casting wash, check for missing stones. Then clip
items off of tree, grind ~ tumble finish.
G. This is a proven technique in lOkt & 14kt yellow gold set
with diamonds, rubies, sapphires,cubic zirconia. All others
subject to experimentation/frustration.
2. Co-ordinate modelmaking with stone setters. Train your wax
people with setters. Apply quality inspections to the waxes
before investing. All wax flaws will faithfully show up in the
3. Be sure to run a large button to assure orderly freezing of
the metal, that is to prevent shrinkage porosity. Sprue with this
4. Flask burnout chart... (All flask temps in Fahrenheit!)
Steam dewax first!
250 to 350 ramp 1 hour
350-450 ramp 1 hour
450-650 ramp 1 hour
650-850 ramp 1 hour
Cast at 850
5. Gold notes- Use a Karated gold that flows no higher than 950
centigrade. Our #21ce or #34 is a good start for lOkt-14kt. Use
the most accurate, fast melt you can. Temp control is essential
to this technique. Be sure to run a large button to assure
orderly freezing of the metal, that is to prevent shrinkage
5. Slow cool flask until you can pick it up by hand, blast off
investment in a enclosed cabinet (if you need to recover stones)
6. Decide how to spend all the setting money you saved.
Do be sure to test these concepts with care. This info was
gathered by Daniel, from the seminar given at MJSA EXPO N.Y.1996,
and from the kind assistance of numerous customers of PMWest.