---
title: "3D model: meaning in gemology"
description: "A 3D model of a gemstone is a digital solid of its facets for CAD, rendering, printing or games. An exact model has flat facets, sharp edges and a closed,…"
url: https://digitalgemology.com/learn/glossary/3d-model
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

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[Glossary](https://digitalgemology.com/learn/glossary) · Cutting and files

# 3D model

Also called gem 3D file, 3D gemstone model

A 3D model of a gemstone is a digital solid of its facets for CAD, rendering, printing or games. An exact model has flat facets, sharp edges and a closed, watertight surface at real size.

## In more detail

A model made to look good is not always made to be cut. Rounded, smoothed or open models cannot be measured. Use a cutting file to cut a stone, and a 3D model to set, render or print it.

## How we measure it

Our models are in millimeters, with the table facing +Y and the girdle plane through the origin. They come as STEP, 3DM, STL, OBJ, FBX and GLB. We build them from the same geometry as the cutting files.

## Related terms

- [Mesh](https://digitalgemology.com/learn/glossary/mesh): A mesh describes a 3D surface as many small flat triangles joined at their edges. STL, OBJ, FBX and GLB files store a mesh.
- [STEP file](https://digitalgemology.com/learn/glossary/step-file): STEP is a standard CAD format that stores an exact solid, with each facet as a true plane. CAD programs such as FreeCAD, Rhino and Fusion open it to measure a stone and design a setting.
- [Watertight](https://digitalgemology.com/learn/glossary/watertight): A watertight model is a closed surface with no holes, so it encloses a solid. In a closed mesh, exactly two triangles share every edge.
- [Convex](https://digitalgemology.com/learn/glossary/convex): A convex stone has no inward corners: a straight line between any two points inside it stays inside. Most cut stones are convex; a heart, with its notch, is not.
- [Cutting file](https://digitalgemology.com/learn/glossary/cutting-file): A cutting file is a faceting design: every facet's angle and index, in cutting order, for a faceting machine. It tells a faceter how to cut the stone.

## Learn more

- [Who uses our files](https://digitalgemology.com/about/files)
- [The 3D models](https://digitalgemology.com/about/how-we-measure/3d-models)

[All 328 terms](https://digitalgemology.com/learn/glossary)