[Jewelry making - Article 00680] - Re: [Orchid] Disappearing diamonds fired in PMC

[Mary Ellin D'Agostino]

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>     I am certainly going to heat up garnets, moonstone and preridot to
>     about 600C for 30 minutes (and longer) and see if they survive.... 

    Hmmm. Many, many people have been doing this for some years now.
    There are several published lists (from reliable sources) indicating
    what result you can expect when heating these stones using metal clay
    firing schedules. Now, if you were to say you wanted to do it so you
    could take and publish before and after microscopic images of the
    stones or give a detailed description of the stones before and after
    using magnification, that would be a great thing. But merely to try
    it and "see if they survive" would be redundant and not advance
    knowledge. 

>     ...but it would be interesting if there was a PMC worker on
>     ganoksin that put a diamond in the oven properly and photograph
>     the results. 

    I think the term "properly" is the key here--you need to define what
    you mean. You obviously have certain expectations of what is "proper"
    and don't feel that the reported results were achieved in a "proper"
    manner. Do you mean a well defined scientific experimental process?
    Although not accompanied by images, the results reported by Kevin
    Whitmore, Art Clay World, myself, and others have been achieved by
    what most people would consider acceptable experimental procedures.
    Not perfect, but good preliminary results. Generally what is lacking
    is the easily found posting on the web of the detailed methodologies
    used to arrive at the reported results. Procedures have been
    presented and discussed at conferences, on the PMC Guild discussion
    board, and the yahoo metalclay list. 

    A more detailed look at the various stones including test firing
    using numerous stones from different sources is what is really
    needed next along with published results and methodology. 

    Garnet is an excellent example of where we need more information and
    systematic testing. Many types of garnet seem to do ok when fired at
    metal clay schedules, though rhodolite tends to darken. As more and
    more people have been experimenting with firing garnets in place,
    there have been reports of trouble--mostly with rhodolite. The
    problem is that it sometimes takes on a dark metallic (think
    polished hematite) surface sheen after firing. The current best
    hypothesis is that the sheen may be a product of heating/cooling the
    iron in pyrope-almandine series garnets or that it is caused by iron
    in (cork clay) armatures sometimes used in making hollow pieces. I
    would love it if a gem expert would take on this question and figure
    out what is going on and why... 

Mary Ellin D'Agostino, PhD
www.medacreations.com
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