3D model and faceting diagram · 76 facets · 6.26 x 5.96 mm
A faceted cabochon: seventy-five triangular facets on a five-fold pattern, rising from a flat pentagonal base to a point. It is widest a little below the middle, and the crown and pavilion triangles meet in a zig-zag at the widest ring, with no girdle band. Drawn for ruby.
Drag to turn
A faceted cabochon: seventy-five triangular facets on a five-fold pattern, rising from a flat pentagonal base to a point. It is widest a little below the middle, and the crown and pavilion triangles meet in a zig-zag at the widest ring, with no girdle band. Drawn for ruby.
Like a cabochon it has no table: it is made to be seen from above and set on its flat base, while every surface of the dome stays faceted.
Measured from the delivered model, not quoted from a standard.
The same geometry behaves differently in every material. Light that meets a pavilion facet at less than the stone's critical angle passes straight out of the back instead of reflecting, which shows face-up as a window. This stone has no table, so the head-on measure used for the other cuts does not apply to it; the table below gives what the model weighs in each stone.
| Stone | Refractive index | Critical angle | Pavilion reflecting head-on light | Weight at this size | Verdict |
|---|---|---|---|---|---|
| Diamond | 2.417 | 24.4° | n/a | 2.00 ct | Not measured: no table |
| Moissanite | 2.648 to 2.691 | 22.2° | n/a | 1.83 ct | Not measured: no table |
| Cubic Zirconia | 2.15 to 2.18 | 27.7° | n/a | 3.30 ct | Not measured: no table |
| Ruby | 1.762 to 1.770 | 34.6° | n/a | 2.27 ct | Not measured: no table |
| Sapphire | 1.762 to 1.770 | 34.6° | n/a | 2.27 ct | Not measured: no table |
| Emerald | 1.577 to 1.583 | 39.4° | n/a | 1.55 ct | Not measured: no table |
| Amethyst | 1.544 to 1.553 | 40.4° | n/a | 1.51 ct | Not measured: no table |
Head-on light, first reflection. The full Light Return, traced in each of these gemstones, is in the 3D Gemstone Simulator.
Open it in the 3D Gemstone Simulator: set its carat, colour, clarity and cut grade in any of seven gemstones, turn it under ten kinds of light, and watch its grading report change as you go. Free, in your browser.
Six formats: STEP (the exact faceted solid for CAD), 3DM for Rhino, STL and OBJ meshes, FBX for Blender, 3ds Max, Maya, Cinema 4D, Unity and Unreal, and GLB for the web and AR. All are in millimetres at real-world scale, with 76 planar facets.
Yes. The cutting files contain a GemCad .asc design (76 facets, 120 index, 5-fold mirror-image symmetry), a tier table with angles, indices and cutting order in CSV, and a printable faceting diagram.
This stone has no table, so the head-on light measure we use for the other cuts does not apply: light enters and leaves through its steep facets rather than through a table. Its Light Return map shows how it behaves in each stone.
We check it facet by facet against the 3D model it was written from. Every crown and pavilion facet within 0.004° of the 3D model (average under 0.001°). The angles are the ones you set on the machine; the 3D model is the same stone you render or set.
The model measures 6.26 x 5.96 x 6.73 mm, which is 2.00 ct in diamond. The same size weighs 1.83 ct in moissanite, 3.30 ct in cubic zirconia, 2.27 ct in ruby, 2.27 ct in sapphire, 1.55 ct in emerald, 1.51 ct in amethyst. Scale it uniformly to any size: weight follows the cube of the size.
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 faceted solid in CAD.
The BL-Cabochon Cut as exact geometry: 76 planar facets, real-world scale, ready for CAD, rendering, printing and casting.
The BL-Cabochon Cut as a faceting design: 76 facets, 120 index, 5-fold mirror-image symmetry, ready for the machine.
Want to know when checkout opens? Email us and we will tell you once.