Casting Stones in Pace

Jewelry Discussion
1

Hi Ken, Have you talked to the people at Romanoff? (800-221-7448)
They did a lot of the pioneer work in this area. I believe
centrifugal will give you better fill. Depending on the size of
the stones and the way you have waxed them in the investment shoul
be strong enough to hold them. J.A.

2

I’ve recently experimented with casting diamonds in place. I
burned out for 3 hours holding the temp at no higher than 800
Farenheit. I didn’t use boric acid. I was surprised to find that
several baguettes chipped or cracked in the process. These were
located the closest to the sprue and I cast centrifugally.

Could it be that the heat shock of the metal (I used a silicon
alloy) entering have caused this? Would vaccuum casting be cooler
and thus easier on the stones? Does anyone know what could have
caused this?

Hoping for answers, Tom Tietze

3

My own experience suggests that care must be take to not allow the
stones to touch each other. I have only cast with diamonds in
place and when they touch each other, they will break.

Bruce D. Holmgrain
e-mail: @Bruce_Holmgrain
http://www.goldwerx.nu
phone:: 703-593-4652

4 
Could it be that the heat shock of the metal (I used a silicon
alloy) entering have caused this? Would vaccuum casting be cooler
and thus easier on the stones? Does anyone know what could have
caused this?

I have been casting diamonds in place for many years and here’s my
method;

  1. one small teaspoon of boric acid to mix in plaster(3x4"
    flask)

  2. all diamonds set in wax must not exactly touch(hair of space
    between them)

  3. burn out to a temp on higher than 1200 and make it alittle
    longer than usual

  4. after metel has been poured I let flask air cool - don’t
    plunge

  5. the hard part is digging out of plaster but have had great
    results I vacume cast but think centrif. should work same. Ron

5

I would like to comment in this arena. There is a material out
here that several are cabbing and csting in place. I mentioned it to
Hale Sweeney and promised to send him some. I have not yet done so
part procrastination and part equipment. I recently bought a 10
inch saw and have just mounted it. Now I will cut some slabs and
send them on to Hale. I have hesitated to bring this forth as there
has been some heated and sometimes nasty debate about this “rock”.
There have beem some exquisite examples of this on display last
year at the Del Mar Fair. I will let Hale have the material I
promised and then after he reports on it, go from there. Teresa

6 
I've recently experimented with casting diamonds in place. I
burned out for 3 hours holding the temp at no higher than 800
Farenheit. I didn't use boric acid. I was surprised to find that
several baguettes chipped or cracked in the process. These were
located the closest to the sprue and I cast centrifugally.

Could it be that the heat shock of the metal (I used a silicon
alloy) entering have caused this? Would vaccuum casting be cooler
and thus easier on the stones? Does anyone know what could have
caused this?

Hi Tom, I believe your flask temp is too low. The molten metal
could easily be double your flask temp, hence thermal shock. J.A.