[Jewelry making - Article 00451] - Re: [Orchid] Diamond cutting

[Bruce Holmgrain]

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>>    The table, being the largest facet is oriented to be nearly
>>    parallel to one of the cleavage planes because that is the
>>    easiest way to polish it. 

>     Actually Bruce, topaz is cut at least 15 degrees off the cleavage
>     plane, as it is hardest to polish parallel to the cleavage plane, as
>     pieces can break off and scratch the facet being polished. 

    The cleavage plane of the cited stone was close to 1 degree of the
    table. I base that in the fact that the break was entirely within the
    girdle. Not parallel, but close. Some time after doing this I read
    that the cleavage plane should be close to the table. I have no idea
    where I read that. 

    This almost validates what you are saying. 

    According to Vargas, "The cleavage plane of topaz must be carefully
    oriented. It should not be less than 10 degrees away from the table,
    and should not be close to parallel to any other fact. 

    According to Sinkankas "When preforming gemstones with good
    cleavages the easiest way to be sure that the cleavage planes do no
    coincide with with any facet is to place the cleavage planes
    vertically in the stone or tilted five to ten degrees from the table
    facet.

Bruce D. Holmgrain
http://www.goldwerx.com
guy AT goldwerx.com
JA Certified Master Bench Jeweler / CAD/CAM Solutions

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