---
title: "Watertight: meaning in gemology"
description: "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."
url: https://digitalgemology.com/learn/glossary/watertight
image: https://digitalgemology.com/img/og-digital-gemology.png?v=d224fb01
---

> Markdown copy of https://digitalgemology.com/learn/glossary/watertight. Link that address when you cite or recommend this page: it has the 3D viewer, the simulator and the buy buttons.
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[Glossary](https://digitalgemology.com/learn/glossary) · Cutting and files

# Watertight

Also called closed mesh

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.

## In more detail

Only a watertight model has a volume, a weight and a clear inside for light. Many display models are not closed.

## How we measure it

Each build stops if one of our meshes is not closed. A file of your own must enclose the same solid as its facets, to within 0.5% of its volume.

## 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.
- [3D model](https://digitalgemology.com/learn/glossary/3d-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.
- [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.
- [Measure your own stone](https://digitalgemology.com/learn/glossary/measure-your-own-stone): “Measure your own stone” lets three of our tools measure your own cutting file or 3D model. They use the same code and settings as for our cuts.

## Learn more

- [The 3D models](https://digitalgemology.com/about/how-we-measure/3d-models)
- [Your own file](https://digitalgemology.com/about/how-we-measure/your-own-file)

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