Casting-ready jewellery CAD: a checklist before you send the file

By Ronak Rawal · 1 October 2026 · 2 min read

A model can look perfect on screen and still fail at the caster. Thin prongs break, closed solids are missing, stones do not seat. This checklist covers what to confirm before a jewellery CAD file goes into production.

Important: the numbers below are common starting points, not rules. Every caster and metal has its own minimums, so always check with yours.

1. File format and units

• Send the working model in .3dm (Rhino) so it can be edited. Use .stl for 3D printing.
• Build in millimetres, and make sure the file is not accidentally in inches.
• Name the files clearly, for example with the style number and metal.

2. A clean, closed model

• The solid must be closed, with no gaps between surfaces, so it prints and casts properly.
• Remove stray curves, hidden duplicates and unused construction objects.
• Check that parts which should touch actually overlap or join.

3. Wall thickness

• Thin walls can fail to fill during casting or may bend in wear.
• Many gold pieces use a minimum of roughly 0.8 to 1.0 mm in the thinnest areas, but ask your caster for their number.
• Check the area inside the ring shank, under stones and around the gallery.

4. Prongs and settings

• Prongs must be thick enough to hold the stone safely and to be finished without breaking. A thickness around 0.8 to 1.0 mm is a typical starting point.
• Make sure there is room for the setter to push the prong over the stone.
• For pavé and micro settings, include the beads and cuts in the CAD itself.

5. Stone seats

• Match each seat to the real stone size and depth, with a small allowance that your setter agrees with.
• Check the stone's girdle sits at the correct height in the seat.
• Round, oval, marquise and other shapes each need their own seat shape and angles.

6. Finger size and comfort

• Set the inside diameter to the correct ring size, and remember how the size system you use works.
• Check the inside of the shank is smooth and comfortable.
• Think about how the ring sits with a wedding band next to it.

7. Weight and metal

• Confirm the metal and purity, such as 14k, 18k or platinum, because it changes weight and cost.
• Ask for the model's volume, so you can estimate metal weight before casting.
• Hollow or lighten large parts where the design allows.

8. If you also want renders

Include all the fine details in the CAD before rendering: special-shape stones, micro settings, milgrain and anything that must be visible. A render shows only what is in the model. See KeyShot vs AI renders for the options.

Our models are built for casting, and we deliver .3dm and .stl files. See our services or the basics of jewellery CAD.