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.
In more detail
STEP keeps exact geometry, while mesh formats approximate it with triangles. A turned girdle can be one cylinder in a STEP solid.
How we measure it
Our facet counts come from the planar faces of each STEP solid. We check every STEP file with the Open CASCADE kernel. Our tools read a STEP cylinder as a ring of flat facets with the same cross-section area.
Related terms
- 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.
- 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.
- Facet count: The facet count is the number of facets on a cut. On our cut pages, it is the number of planar faces of the cut's STEP solid.
- Turned girdle: A turned girdle is a girdle with a smooth round edge, shaped as a cylinder, instead of flat girdle facets. CAD often gives a round stone this kind of girdle.