[Jewelry making - Article 00115] - Re: [Orchid] More Opal Setting

[Derek]

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    Opal indeed has many myths around it.  I've cut a great many stones
    mostly Australian solids: crystals, whites, some blacks.  I've made
    doublets and triplets which can also be fun. 

    It seems like locale is the primary predictor of stability in opal. 
    The Aussie stuff seems generally stable, though I'm sure there are
    exceptions (one of which I'll mention later).  Boulder also seems
    stable, albeit the layers of opal can be so thin that they crack
    easily.  

    Mexican opal is surely unpredictable and may craze quite a long time
    after cutting. I hate it when it does that.  I had one pull that
    little trick 6 or 8 months after cutting.   

    Idaho and Nevada I haven't cut, but have been told are frequently
    unstable although I understand some Virgin Valley is cuttable.  Same
    is true for Honduran and   Brazilian.  Some of that stuff will go
    completely white when out of water.  In common opal without fire but
    that is till quite pretty, Andean is mostly unstable, but the newish
    pink Baja California find seems stable.  I've had some on my bench
    for months will no ill effects.  I have also heard that the
    relatively newer Brazilian find with fire is more stable, though I
    have no proof of that. 

    So most of this is what I've heard or read. But the Aussie, old
    reliable is still just that, relative to the others, reliable. 

    All that having been said, I find that opal is rather fragile.  It
    is not only fairly soft but also highly temperature sensitive,
    especially heat and extreme cold, like below zero.  

    It also cracks fairly easily when struck which makes it
    inappropriate in a ring for people who insist on using their hands a
    great deal while wearing the ring.  On the other hand (no pun
    intended, I'm sure), I have a bezel set doublet in a ring I made for
    myself years ago. 

    I wear it frequently and it's still whole.  I know it gets some
    abuse because I have to polish out scratches from time to time.  I
    did put a backing in the bezel with a cushion of rubber.  That might
    have helped it.  

    I have to say in general that I think opal is especially
    inappropriate for prong set rings.  I know many people like that,
    but it seems too vulnerable for such a soft stone. It is after all
    not that much harder than solid turquoise.  Also there seems to be
    too much potential for stress at too few places.  One good rap can
    do it in. 

    Still as long as the buyer is properly warned, I don't see how you
    can prevent people from taking a risk. 

    One other thing with opal that can be a problem. Once older material
    has been scratched, even the Aussie stuff, polishing it can make it
    unstable.  I don't know why that is but I've had more than one
    person warn me off messing with older set opal. 

    All of that personal experience and hearsay now laid out, I can say
    that I really do love opal.  It was the first species of stone I
    started cutting and the fascination has never completely worn off.  

    The orientation on opal and problems associated with cutting it
    makes uncovering a true gem such a thrill. 

    And also exceptionally good material is so rare, especially in the
    Lighting Ridge black. 


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