3D model · 8 faces · 10 mm circumsphere
Eight equilateral triangles, meeting four at each of six vertices, dual to the cube. It is the shape that rough diamond grows in most often. Spinel and magnetite have the same habit.
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Eight equilateral triangles, meeting four at each of six vertices, dual to the cube. It is the shape that rough diamond grows in most often. Spinel and magnetite have the same habit.
It is also where the brilliant began. The single cut is an octahedron with the top point ground away for a table and the corners beveled. Every brilliant since then comes from it.
See the Old Single, rebuilt in our historic cuts.
Taken from the delivered model. We check it against its mesh every time we build this page.
Six formats. STEP is the exact solid for CAD, and 3DM is for Rhino. STL and OBJ are meshes. FBX is for Blender, 3ds Max, Maya, Cinema 4D, Unity and Unreal. GLB is for the web and AR. All are in millimeters at real-world scale, with 8 flat faces.
No. We sell the Platonic solids as 3D models only, with no faceting design, tier table or diagram.
Resting on a face, it measures 8.165 x 7.071 x 5.774 mm. Every vertex is on a sphere 10 mm across. All five Platonic solids share that sphere, so they nest and sit together at true relative size. You can scale it uniformly to any size: for a 10 mm edge, scale by 1.4142.
Y up, with one face resting on the ground plane and the centroid on the Y axis. The midpoint of one edge of the resting face lies on the +X axis. This keeps the cube square to the axes.
Yes. The mesh is watertight and manifold, with outward normals and no duplicate vertices, so it prints and casts without repair. Use the STEP file when you need the exact solid in CAD.
The octahedron as exact geometry: 8 flat faces, real-world scale, ready for CAD, rendering, printing and casting. We sell the Platonic solids as 3D files only.
Save with a bundle: the octahedron 3D files are also in Platonic Solids Set, 5 solids for €7.49 until 1 December, then €9.99 (€19.95 as single files). Buy the bundle.
Not sure the files open in your software? Get the cube free: the same six formats, for your email address, used only to send them (privacy).
Questions before you buy? Email us.