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Thread: RANT! Don't heat stones !

  1. #1
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    Default RANT! Don't heat stones !

    I don't know why I feel so strongly, but I do.

    When we heat treat stone to improve the color etc. we use temperatures in the 400 to 600 range. I keep seeing stons destroyed by soldering or worse setting them in PMC and firing.

    The problem is, the books I read are advocating it! Sure why not have a lottery!

    Sorry but something had to be said

    Julian

  2. #2
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    Not even diamonds, Julian?

  3. #3
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    Hmmm well I have successfully heated some stones, though I would not risk a diamond, my most notable failure, as I did not know any better, was aquamarine which explodes into thousands of sparkling pieces. Blue czs go a rather attractive shade of coca cola, which is fine if you really did not want a lovely blue. Rubies when cooling look like they have not fared well but by the time they are back to room temperature are the same as they were before being roasted. I am still waiting on my kiln and have some songea sapphires which are going to be cooked and a couple of garnets. I will let you know if I in fact win or lose the "lottery" :0)

  4. #4
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    Quote Originally Posted by Dennis View Post
    Not even diamonds, Julian?
    Asking that question, I had in mind an article about multiple tube setting of diamonds, which I could not find today.

    The tube is held in the handpiece of a flex-shaft and rotated against a burr to create the seat. Then the diamond is inserted and set by pressing a burnisher against the rim of the tube while it spins. Next the unit is cut off by rotating it against a saw and so on.

    Once you have enough ready set units, they are soldered on to the piece. What do you think? Dennis.

  5. #5
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    Interesting idea Dennis. Not sure that the benefits outweigh the risk though.

  6. #6
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    Quote Originally Posted by Dennis View Post
    Not even diamonds, Julian?
    Your diamonds, but not mine. Frankly they should be safe from discoloration if you don't add pressure, but there is a large risk of cracking. When we (gemologists) look for signs of heating, we look at the damage done to the inclusions, not thecrystal itself.

    A bad inclusion, could cause a stress fracture in th crystal.

    Julian

  7. #7
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    Then I suspect you gemologists should not play the pyro lottery and leave it to us who have more of a sense of adventure and don't mind setting the curtains on fire with chips of red hot tourmaline flying round our racy ears :0)

    albeit that sometimes you end up with something quite lovely that may have cost you a bit in the getting there :P
    Last edited by Kwant; 18-06-2012 at 07:15 PM. Reason: added alacrity

  8. #8
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    Quote Originally Posted by Kwant View Post
    Then I suspect you gemologists should not play the pyro lottery and leave it to us who have more of a sense of adventure and don't mind setting the curtains on fire with chips of red hot tourmaline flying round our racy ears :0)

    albeit that sometimes you end up with something quite lovely that may have cost you a bit in the getting there :P
    roflmao, I am up for a BBQ any time

    J
    Last edited by Julian; 18-06-2012 at 07:39 PM. Reason: Toned down!

  9. #9
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    Casting diamonds in place is becoming more popular there is even special investment to do this just remember to never quench the flask in water

  10. #10
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    Quote Originally Posted by josef1 View Post
    Casting diamonds in place is becoming more popular there is even special investment to do this just remember to never quench the flask in water
    yup... my casters do stone set wax casting. I fired an artificial emerald in pmc once. it didn't fare well although the colour is fine and I quite liked the rather organic shape it became.

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