[Jewelry making - Article 00069] - Re: [Orchid] Characteristics of real jet beads

[Peter W. Rowe]

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>     Is there a sure fire way to discern jet from crystal or resin
>     without chemical testing? I greatly appreciate your help! Vera 

    The very light weight is one obvious indication of jet.  Jet is
    actually a form of coal, not a resin.  You can tell it from it's
    streak (rub it lightly on a bit of tile or unglazed ceramic.  The line
    it leaves is dark brown).  This test should only be done on an
    inconspicous area, though, since it mars the piece of jet.  If you
    can find a tiny chip (with a loupe), it will be dull and grainy
    looking, not shiny and glassy.  Another classic test is the "hot
    point" test.  Touching the piece briefly with a red hot needle in an
    inconspicous spot will show different results with resins (which melt
    and emit a smell) vs jet, which emits only a mild smell, vs crystal,
    which does nothing.  Whether you can tell jet this way depends on your
    sense of smell though, and again, it's a test that can leave a mark on
    some materials. Use a loupe to watch the reaction as you touch the
    piece, and use only the tip of a sharp point, red hot, and you won't
    leave a large mark.  And jet, like crystal, but unlike many plastics,
    will crumble/powder in front of a needle or sharp blade, while many
    plastics and resins will let the blade "bite" in, raising a tiny
    curl. And finally, some, but not all, jet will be porous enough to
    absorb moisture, so that if you put a tiny drop of water or saliva on
    it, it will appear to dry off faster than it would on non-porous
    materials.  This isn't always visible, but when you see it, it tells
    you that the material is not glass (crystal) or plastic... 

Peter Rowe


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