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HOLYCOME Fine jewelry · since 2008
How to design a custom engagement ring (without a design degree)

How to design a custom engagement ring (without a design degree)

What to decide first, what a CAD render should show you, and the three measurements that prevent an expensive mistake.

Custom design goes wrong for predictable reasons: the stone is deeper than the setting allows, the band is too thin for the head, or the wedding band will not sit flush. None of these are taste problems. They are measurements, and they can be settled before anything is cast.

1. Start with the stone, not the setting

The stone sets the geometry. A 2 ct oval is roughly 10 × 7 mm; a 2 ct round is about 8.1 mm across. Those are different footprints, and they change how wide the shoulders need to be.

  • Shape — round reads classic and hides colour; oval and pear elongate the finger; emerald and asscher read architectural; marquise is the most polarising.
  • Depth — a deep pavilion sits high above the finger. If you want a low ring, ask for the depth in millimetres, not just the carat.
  • Material — moissanite for fire, lab-grown diamond for diamond optics, lab-grown colour if the stone is the point.

2. Decide the setting height early

A high gallery shows more of the stone from the side and lets a straight wedding band sit close. A low gallery is more practical and catches less, but it often needs a curved band.

Ask for the gallery height in millimetres and the total spread across the finger. A ring that is 8 mm tall on a size 6 finger looks very different from the same ring on a size 4.

3. Band width and thickness

2 mm is delicate and best with a small centre. 2.5–3 mm is the everyday middle. 4 mm and up reads as a men's band or a statement. Thickness matters as much as width: a 2 mm wide band that is 1.2 mm thick will distort; the same width at 1.8 mm will not.

4. What a CAD render should show you

A useful render is not a pretty picture. Ask for:

  • Three angles — top, side profile, three-quarter.
  • Dimensions written on the image: band width, gallery height, stone diameter.
  • The wedding band drawn next to it, if you are buying both.
  • Your ring size, so the proportions are relative to your hand.

If a supplier sends one glossy image with no dimensions, you are looking at a sales asset, not a design.

5. Approve in writing

Approval of the render is approval of the design. After casting, dimensional changes mean cutting and re-welding metal, which is expensive and never invisible. Put the final spec — metal, stone, size, width, engraving — in one email and ask for confirmation.

6. Budget for the right things

Money is best spent on the stone and the setting, in that order. A bigger stone in a thin setting is a repair waiting to happen; a smaller stone in a well-built setting looks better for longer. The metal is the cheapest part to upgrade and the most expensive part to fix.

7. Timeline

CAD: 3–5 business days. Revisions: as long as you need. Production: 3–5 business days after approval. Shipping: 3–10 business days standard. Work backwards from the date you need it and keep a two-week buffer for the unexpected.

If you want a second opinion on a spec, send it to us — we will tell you what will not work before you spend anything. Request a quote →

Last updated November 5, 2026. Something out of date or unclear? Tell us — we correct these pages.

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