Forums Article Discussion Incorrect angle

2 replies, 2 voices Last updated by  JTheesfeld 1 week, 1 day ago
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  • #5342

    gemcutter1
    Participant
    @gemcutter1

    I am trying to cut the Antique Oval by Nancy Attaway. The #1 cut on the pavilion is wrong. I tried a number of angles and 45.93 seems to work. The 52.93 is wrong.

    #5343

    gemcutter1
    Participant
    @gemcutter1

    I was continuing to cut and the #4 cut came out wrong. The angles for this stone are wrong. If the # 1 cut is correct, then the #2 & 3 angles are wrong.

    #5344

    JTheesfeld
    Participant
    @JTheesfeld

    Gemcutter1

    GemCad typically does not lie. This cut works as shown, with the angles listed, but you may need to use a different process to get it right. This is not at all uncommon.

    This design is the perfect example of the value of using the CAM method to cut a gem. CAM is “Centerpoint Angle Method” CAM for short. The sequence listed for this gem results in an estimated facet length when going from G1 to 2. It is not “meet-point” faceting friendly as shown. In order to cut this gem in 100% meet-point fashion, you would need to re-sequence (not the best way), or use a CAM preform.

    CAM Design

    If you learn to use the CAM preform, you will establish the exact girdle outline first, by using temporary center-point facets, which will be eventually, cut away. I use this method all the time, to avoid the situation you seem to be describing with your efforts. This does require you to use GemCad, or GemCutStudio, to create a CAM preform design first. I completely recommend this to everyone.

    I suspect that when you cut your #2 tier, that you had to estimate your G1 length, which is inherently inaccurate, thus causing the angle issues you describe.

    I hope this helps.

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