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| Re: [Orchid] Characteristics of real jet beads | ||
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From: Peter W. Rowe Date: Tue Nov 02 17:38:54 1999 |
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========[ Invite a Friend - http://www.ganoksin.com/invite.htm ]======== > 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 ____________________________________________________________________ T h e O r c h i d L i s t Open Electronic Forum for Jewelry Manufacturing Methods and Procedures ____________________________________________________________________ Orchid FAQ: ~ http://www.ganoksin.com/orchid/faq.htm Orchid Archives: ~ http://www.ganoksin.com/orchid/archive Orchid Galleries: ~ http://www.ganoksin.com/orchid/gallery.htm Invite a Friend: ~ http://www.ganoksin.com/invite.htm ____________________________________________________________________ Tips From The Jeweler's Bench - Article Archive ~ http://www.ganoksin.com/borisat/tip_sear.htm The Jeweler's Selected Bibliography List ~ http://www.ganoksin.com/jewelry-books Buy Orchid Jewelry: ~ http://www.ganoksin.com/shop ____________________________________________________________________ -Unsubscribe: -Email: orchid-request AT ganoksin.com Body=unsubscribe subject=blank ____________________________________________________________________ |
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