What is a CAD model and how is it used in custom ring design?
About sixty percent of the custom rings I make start with a CAD model. The other forty percent start with wax carvers, hand-fabrication from sheet and wire,...
About sixty percent of the custom rings I make start with a CAD model. The other forty percent start with wax carvers, hand-fabrication from sheet and wire, or-my favorite-a client's napkin sketch and a lot of staring at my bench pin. But CAD is the workhorse, and it's worth understanding what it actually does before you commission a ring.
A CAD model, at its simplest, is a digital blueprint of the ring. I build it in Rhino 3D, usually, though I know jewelers who swear by MatrixGold or even Fusion 360 for the parametric controls. The model captures every dimension-shank width at its thinnest point, prong height, stone depth, the exact curvature of a cathedral shoulder. I work in millimeters and tenths of millimeters. A client once asked me to "eyeball the symmetry." I do not eyeball symmetry. I measure it.
How CAD actually gets used in a custom job
The process usually goes like this: after the consultation-where I've taken measurements of the client's finger, discussed the stone, and shown them reference images-I build the first pass in CAD. This takes anywhere from two to six hours for a straightforward solitaire, longer for something with pavé or engraving or a specific vintage-inspired profile. I send the client a set of renders from multiple angles, plus a short video rotating the model. Most clients respond within 24 hours with exactly one change: "Can the band be a little thinner?" or "The prongs look too big." Both of those are fair questions. The thinness issue is almost always a safety concern-I won't go below 1.6mm for a shank, and I usually recommend 2.0mm for a ring that will be worn daily. The prong question is about proportion; I'll show them reference rings on my hand to give scale.
The real value of CAD is that it catches problems before metal is cut. A model will show me, for example, that the culet of a deep-cut old European center might hit the top of the finger if the stone is set too low, or that a particular hidden halo design will make the ring impossible to resize later. I can fix those things on screen in ten minutes. In metal, it's a full-day re-do, if it's fixable at all.
The step you don't see: the resin model
Once the client approves the CAD, I don't go straight to casting. I print a resin model. This is a physical copy of the ring in a hard wax-like resin, produced on a 3D printer-I use a Phrozen Sonic Mini for this, and it takes about three hours to print a band. The client gets to hold the resin model, try it on if they're in the studio, feel the weight and width. This is where the real decisions happen. A 2.2mm band that looked elegant on a screen can feel flimsy in the hand. A 3.0mm band can feel too heavy. I'd say one in four clients changes a dimension after holding the resin model. That's fine. It's why we do it.
The resin model is then used in the lost-wax casting process-it's burned out in a kiln, leaving a cavity that's filled with molten metal. So the final piece is a direct translation of the CAD, filtered through a material it was designed for.
What CAD can't do
Here's the part you don't hear from the CAD-render-driven Instagram jewelers. A model can get the geometry right, but it can't get the finish right. It can't tell you how a hand-milled bezel will catch light differently than a machine-finished one. It can't replicate the feel of a prong that's been filed and polished with a mizzy wheel to a specific softness. I've seen CAD models that look perfect on screen and produce rings that feel dead in the hand-too sharp, too uniform, too much like a machine made them. Because a machine did.
I use CAD. I also hand-finish every piece I make. The model gives me the skeleton. The bench work makes it a ring.
What to ask your jeweler about their CAD process
- What software do you use? Rhino, MatrixGold, and ZBrush are the main ones for jewelry. If they say "a friend does it for me," ask to see examples of their friend's work on completed rings.
- Will I see a resin model? If the answer is no, that's a red flag. A resin model is the cheapest insurance against a finished piece you hate.
- How many revisions are included? Two to three is standard. More than that and either the design isn't right or the CAD work is sloppy.
- What changes between the model and the finished ring? The answer should include finishing details-milgrain, texture, hand-engraving-that can't be properly CAD'd.
The best custom ring is the one where the CAD model is a conversation starter, not a final answer. The worst is the one where the client never sees the model, or where the model is treated as the end of the process instead of the beginning.