Forums Article Discussion Problem cutting cz

7 replies, 6 voices Last updated by  chuckgartmann 1 month, 2 weeks ago
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  • #5316

    BruceM
    Participant
    @BruceM

    Has anyone experienced this problem with CZ. Picture attached, after prepolish with 1200 lightinglap. The entire facet does not polish the same . The entire stone seems to have faint lines showing a geometric design within the stone.

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    #5318

    Rick_Brooker
    Participant
    @Rick_Brooker

    The picture does not show a close enough view to get a good perspective. If you are at 1200 have you cut away enough material to remove the stress cracks from the rough cutting?

    #5320

    BruceM
    Participant
    @BruceM

    Hi Rick ! Thanks for responding . If you tap on the picture it should become larger and easy to see what I’m talking about. It’s really strange , I’ve cut the pavilion 3 times and does not appear to be a stress crack. I’m beginning to think it’s a manufacturing error or at least something that happened during the process of manufacturing.
    I’ve checked all of my batch of cv and have found the same situation on most of the pieces.

    #5322

    Rick_Brooker
    Participant
    @Rick_Brooker

    Not all man made stones are perfect. You can have impurities and inclusions from the manufacturing process. If you buy without being able to inspect the piece you take your chances. I hope you didn’t over pay for that batch.

    #5348

    jasonking
    Participant
    @jasonking

    So after cutting the pavilon you have facets showing inside the stone like internally?

    #5399

    gailbumala
    Participant
    @gailbumala

    Bruce M,

    I’m curious, did you finish cutting that CZ?
    Did you find something to remedy your issue?

    #5437

    MSackos
    Participant
    @MSackos

    To me, it appears that one facet cuts slower than the rest. I have experienced that in a number of other stones, including lab created stones. However, I am not certain this is your issue as I do not cut a lot of CZ.

    Here’s my CZ secret: The only time I cut CZ is if I’m in some type of competition…then….what I do is…go online and buy an already cut CZ a little bigger than I need and of a similar shape as I need for the competition (like a standard round brilliant), the stone is cheap enough that I can basically treat it as preformed piece of rough. Then I just re-cut it! The advantages are that I already know how vivid the finished color will be, I already have a good preform to save time, I already can see there are no inclusions (although this isn’t a problem with CZ), and I already can see that someone cut/polished the stone before…and I can assume they didn’t have any major problems!

    #5455

    chuckgartmann
    Participant
    @chuckgartmann

    I hope you are finished with the stone, but just in case! This looks like insufficient prepolish.
    1200 is much too coarse for CZ in my opinion. I suggest you step thru 3000 and then 8000 as the
    final prepolish. Not only do you need to get rid of the scratches from the previous grit, but also
    the stress fractures from previous grinds. CZ is hard and grinds very slowly on prepolish, best
    polish is after an 8000 grit prepolish. It is hard to judge from a photograph without seeing the
    actual stone.

    I just finished a 18mm CZ stone and had very similar facet appearance even when 3000 looked good.
    At 8000 it took forever to grind out those previous under lying blemishes. CZ can have various
    directional hardness across the facets depending on what chemical makeup is used by the manufacturer.

    Chuck G.

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