[Jewelry making - Article 00857] - Re: [Orchid] Grams per carat - opals question

[Dave Sebaste]

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Hi Tom!

>     1.  What is the standard conversion between grams to carats for
>     opals? 

    There are five carats to the gram, regardless of the gemstone. To
    get a reasonably accurate weight, you need a scale that will weigh in
    1/100 of a gram. a 1/10 gram scale can only be converted to the
    nearest 1/2 carat. For opals, this may be accurate enough
    ("ballpark") but for finer/smaller stones, you'd need greater
    accuracy. 

>        2.  How do I factor in the ironstone backing on the doublets? 

    If its an ironstone backing, its most likely a boulder opal or seam
    opal. A doublet is constructed, and usually has a black backing
    piece, such as onyx or basinite. If it is indeed a boulder opal, I
    don't think you need to factor in the matrix, or backing material.
    Sell it as a boulder opal, by weight, and the buyer should
    understand. Doublets and triplets are typically sold by calibrated
    size, rather than carat weight. 

    Hope this helps! 

Dave

Dave Sebaste
Sebaste Studio and
Carolina Artisans' Gallery
Charlotte, NC (USA)
dave AT sebaste.com
http://www.CarolinaArtisans.com 


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