Forums General Discussion Girdle Size

  • Girdle Size

    Posted by wilbertfwebb on January 12, 2018 at 6:36 pm

    I’ve been of the opinion that girdle size is too be as described in contest rules and always use that as a guide. Recently I used a larger dopstice to hold the pavillion and the girdle depth was hidden from view so I cut with caution. When I finished and stone was removed from the dop I had a larger than normal girdle depth for me. I was taken back at first and the next morning I viewed the gem again after mounting in a ring setting and it actually looked rather nice.
    It there a hard fast rule on this subject? I am attaching a picture of a quality diamond set in a ring and the girdle is noticeably large based on the gem size.

    Bert Webb
    Sophia, N.C.

    scottwkelley replied 6 years, 6 months ago 4 Members · 6 Replies
  • 6 Replies
  • Alan Balmer

    January 13, 2018 at 2:51 am

    Hi, Bert. This is a subject that there is not much agreement on 🙂 If you know any jewelers, you might ask them their opinion. I think there is pretty general agreement that the 0.3mm usually specified for USFG competition is too narrow for settings. I personally tend to have thicker girdles on larger stones. If there are no other constraints, I cut until it “looks right” to me.

    • wilbertfwebb

      January 19, 2018 at 5:57 pm


      Thanks… as always you make the path a little clearer. 👌


  • michaelnoetzel

    January 18, 2018 at 11:29 pm

    Hi Bert:

    Proper girdle size relates to intent. The .3mm specified in the USFG gives an additional challenge to competitors to cut and measure their stones to this smaller, more critical dimension but it also allows judges to better see whether the girdle line(s) are level/parallel. With a thinner girdle, unevenness sticks out easier.

    However, this thinner girdle (depending on cut to a degree and the material of the stone) is too delicate for most jeweler’s tastes because there is a real danger of them cracking a stone while setting it. I don’t have much experience setting stones so when a coworker asked me for some help with an anniversary gift of a ruby to be set in a ring he had already purchased, I acted as an intermediary between a local jeweler I have done business with and my friend. The loose stone was purchased on Jewelry TV and was an off size, as was the ring he brought in. My guy can work around the off-size issues but the ruby had a large ugly pit in it, very near the edge of the stone which had a fairly thin girdle as it so happened and no pavilion (there was no need with this opaque material).

    When inspecting the stone I saw the pit at a distance with my naked eye so you can imagine its size. I brought it to the shop and my guy was a little intimidated to try setting it as-is. He initially wanted to relocate prongs away from this vulnerable area but after sitting with it for several minutes at the bench, decided to go for it and I was really thankful the stone did not crack. I don’t know what my friend paid for the stone. He seemed proud of his purchase (as if he had spent a fortune) but I looked at a cloudy, poorly cut ruby and shook my head at the thought that he wished to proudly present this to his wife of 50 years whom he adored.

    For my taste, I would cut a girdle a little thinner than what you show in your photograph, perhaps about 80% of what you have. There is a sort of feng shui consideration (rules of proportion) that you need to employ. If the girdle is thick enough to be visually distracting from the rest of the cut, it is too thick. Basically when you look at the stone you should not notice that the girdle is there, but it needs to be thick enough to be sturdy and of course there is the idea that a thicker girdle allows for slightly more carat weight and a little deeper color saturation.

  • wilbertfwebb

    January 19, 2018 at 5:55 pm


    Thanks for you input on this subject. I now am of the opinion to form the girdle to be small enough or large enough to be secured nicely within the prongs without losing the aesthetics of the finished gemstone and be smaller in size then the pictured submitted gem… unless I’m entering a stone in the guilds contest.

    Thanks for you suggestions.


  • Alan Balmer

    January 19, 2018 at 6:48 pm

    “secured nicely within the prongs without losing the aesthetics of the finished gemstone ”

    A good way to put it.

  • scottwkelley

    January 22, 2018 at 7:25 pm

    So far everything I have set into silver set best with a thin girdle. believe it or not but a .5mm girdle might be to thick. I also think that a thinner girdle sometimes give off more sparkle in the stone, depending of coarse. These days I strive for a thin girdle and use a paintbrush hair as my .2mm gauge. Now that is thin.

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