[Jewelry making - Article 01223] - Re: [Orchid] Fire opal question

[Hans Durstling]

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Hi Peggy,

    First let's make sure we're talking about the same thing. I'm taking
    fire opal to mean the reddish to honey colored transparent to
    translucent opals which may or may not have play of color that
    typically come from Mexico although there are other locations. 

    To answer your question no they don't always go opaque in sunlight.
    But some do. In my own experience these are a minority. I had one
    nice approx 3 carat step cut Mexican which after a year had
    developed a cloudy white patch with a crescent-shaped crack around
    it. Many, indeed most, others have stayed stable for years. 

    A recommended practice for Mexican and other susceptible opal is to
    leave the rough out in the sun for six months or a year. If it
    hasn't altered after that, it probably won't. Probably is the key
    word. There are no absolutes but it's a reasonably safe bet. 

Cheers
Hans Durstling
Moncton, Canada

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