A planar facet is a facet that lies exactly in one flat plane. Real cut stones and our models have planar facets; curved or smoothed display models do not.
In more detail
A gem refracts correctly only when its facets are truly flat. A flat facet keeps a beam together, and a curved one spreads it. So a rounded, smoothed or scanned model cannot be measured as a cut stone.
How we measure it
Our tools group a model's triangles into facets by the plane they lie on. A model that breaks into more than 2,000 flat pieces counts as a scan or a smooth shape. The tools do not measure it as a cut.
Related terms
- Facet: A facet is one flat, polished face of a cut gemstone. Its angle and its direction around the stone decide where it sends light.
- 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.
- 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: “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.