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Trouble Determining Cabochon Size

Hello everybody,

I’ll start off by saying that I don’t make jewelry myself, but I was hoping some of you could share some of your expertise with me.
I’m looking to have a custom ring made, and I’m still trying to get an idea of what I want, but I don’t quite have the information I’d like to begin, which is why I’m posting this.
Basically, I’m looking to have a bezel set ring made (it will be cast) with a square cabochon stone. It will be a masculine ring, so it will be rather large, of course, but I also don’t want it to be huge. I’m going to have the cabochon cut from a slice of agate at a local lapidary, and I was just wondering if anybody could help me decide how big I should have them make it. Looking at rings I already have, I’d prefer for the stone to be 8-9mm (visibly). I have larger ones as well, but I don’t like rings that are too big. My main question for this part is how big should the cabochon actually be? I was thinking about having 1.25-1.5mm of metal covering it on the sides, but I’m not sure if that’s too much or too little. One of the rings I already have with a 10mm stone has 1.75mm of metal covering it on all sides, which I think looks too thick. I’d mainly like to know how thick the bezel should be to be sturdy and secure, but also not super huge, like a large frame. In addition to this, I’m not sure how thick to have them make the cabochon. What would be a good thickness for a cab to be resilient but also not so thick that it rests 6mm or more off of the finger? Is 3mm a good thickness, or is that too thick? Maybe 4mm would work better; I really don’t know.
Preferably, I’d like the maximum thickness of the ring to be 10mm wide with an 8mm (visible) gem. I say visible because I know some of it will have to be covered by the bezel. I’m willing to go up to 11mm as well, but that’s about the limit for me, so I’d like to know how big the cabochon needs to be in order to fit into such a setting. I’m also fine with making the cabochon smaller if that’s what needs to happen. So long as the stone is secure, and the bezel isn’t too thick, I’m fine with it, so any help would be greatly appreciated.

Thank you!

Talk to the jeweler who is making the wax and casting. If you are trying to do it yourself, be prepared to do it several times. For openers, waxes shrink…

Well, that’s just it; I don’t have a jeweler picked out yet since this isn’t a time-sensitive project. I’d like for the ring to be based around the stone, so that’s why I’m trying to get an idea of how large the cabochon should be. Do you happen to know how much material would cover the stone on each side? If I wanted to be able to see 8mm of the stone, would it be better to go with a 9mm stone or a 10mm one in your opinion? I also attached a couple of images of a ring I found online that I like the bezel on. That’s kind of what I’m going for, a thin bezel with a low profile, so I’m trying to figure out the dimensions for a setting like that. The stone in the reference photos is 7.5 x 7.5mm if that helps at all.

Since you have a photo of the ring you like face on, why not just measure it? Find your size and its diameter and then measure the diameter of the ring on the screen. That will determine the magnification of the photo. Then measure the width of the stone and the width of the bezel and use the magnification factor to determine their actual size on the ring. Take any other measurements you need and you’re done. QED…if you’re still not sure you have what you want, get a small piece of balsa wood from a craft store, carve a replica and see how you like it on your finger…might even be able to do a mock-up with cardboard, paper, paste and sandpaper…royjohn


I had a couple of thoughts…

  1. your picture shows a stone that has been ground down/ polished “flush” with the bezel setting. (or, it is enamel…?)

is this the look you desire?

If so, I am thinking that the sides of the stone are chamfered/ beveled at an inward angle, with the top “face” of the stone being smaller than the bottom of the stone, and the bezel is hammered at a downward angle. This would move the metal downward/ inward to “trap” the stone in place.

then, the whole top of the ring (bezel and stone) are ground/ polished flat flush.

since the stone is chamfered/ beveled and the sides, this will be enough to trap the stone, and no metal needs to "roll over the top of the stone.

the difference between top and bottom of the stone can be as little as 1 mm…as long as the bottom is bigger, it will not come out. In reality, in terms of holding a stone in place, as long as say 3 points make contact, it should stay in place…
so, with that said perhaps your stone could be 8x8mm along the top, and 10x10
mm along the bottom? I would suggest to soften all edges so they do not chip in setting…?

as far as the height of the stone goes, I would take your desired overall ring height, at top, and minus a minimum of about 1.0-1.5mm for “stone above finger” (the open part under the stone…the “hollowed out part”…

the ring in the photo does not look that tall…

i would venture to say that if you have looked at your current rings and feel that 1.75mm wide bezel is too thick, then perhaps .80mm=1.0mm would work for you…it will get wider as it is hammered down/ spread…

as a point of reference, note that fine silver (soft) bezel wire is extremely thin, and is commonly offered in thicknesses of .25mm, .33mm, .41mm, .51mm.

hope this help you think it all through…


1 Like

Thank you so much for that reply! This is the type of response I was looking for.
As I said, I don’t make jewelry myself, even though I’d like to, but I’ve seen videos galore on the subject, and when it comes to actually gathering the materials to make jewelry items, I’m at a loss.
I was just wondering about having an angled stone today when I saw it on another ring of mine, so I’m glad to know that will work, but I didn’t think of grinding down the bezel to make it flush with the stone. If that’s done, how do you ensure that there are no holes in corners because it’s a square, or do the angles on the stone prevent it? Also, is that setting still possible to do with a cast piece, or do you need to use bezel wire, or maybe a mix of both? Lastly, if the metal was to be hammered over the stone, would it need to have an angle going up, sort of like a pyramid shape so it can become flat once it’s hammered, if that makes any sense? Sorry to bombard you with questions, but I’ve had a very difficult time trying to find this information elsewhere, and you seem quite knowledgeable about the subject.


—if you have the stone in hand, and show a photo, along with specs to a jeweler, then they will be able to figure out how to construct the ring. I would venture to guess that this type of signet ring is best suited to being designed in CAD/CAM or carved in wax, and then cast into your desired metal choice.

Also note that the bezel itself will be “one” with the rest of the wax carved/ cast ring…one homogenous object. and can also be further defined/ refined/ shaped/ filed/ polished, after the stone is set. The bezel start"open" and the bezel metal is manipulated to be compressed to the stone—


Hello Austin,
I think you are overthinking this…if you give the jeweler who is going to make the ring a picture of what you want, then they can easily devise a way to set your stone. If you want the stone ground down flush, state that. You could also have the same type of thick bezel and a domed stone, it would be your choice.
There are various ways to set such a stone (either flush or not) without leaving any holes…grinding down, burnishing down, etc. It could even be set from behind…it depends what the jeweler wants to do and the dimensions of the stone.
What you need to do is give the jeweler a sketch or picture and description of what you want and leave it to them to figure out how to set the stone. I’m sure they can describe what they are going to do to your satisfaction. Worrying over every little detail without knowing what the jeweler’s plan is makes no sense. -royjohn