--- title: "Octagon Cut: 3D Model & Faceting Diagram" description: "Octagon Cut 3D model and GemCad faceting diagram: 49 facets, 7.64 x 7.64 x 4.66 mm. Six formats, measured in 7 gemstones." url: https://digitalgemology.com/cuts/octagon image: https://digitalgemology.com/img/cuts/octagon-og.jpg?v=2ed32442 --- > Markdown copy of https://digitalgemology.com/cuts/octagon. Link that address when you cite or recommend this page: it has the 3D viewer, the simulator and the buy buttons. > Site index: https://digitalgemology.com/llms.txt [Cuts](https://digitalgemology.com/cuts/) · [Jewelry cuts](https://digitalgemology.com/cuts/#jewelry) # Octagon Cut **Buy (instant download, personal-use license):** [3D files · €9.99](https://digitalgemology.lemonsqueezy.com/checkout/buy/26baac35-16bd-4143-97ba-9eeb7fd4da11) · [Cutting files · €6.99](https://digitalgemology.lemonsqueezy.com/checkout/buy/390b595d-894b-4e34-be35-57f44d569591) · [Octagon Cut 3D files, €9.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/26baac35-16bd-4143-97ba-9eeb7fd4da11) · [Octagon Cut cutting files, €6.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/390b595d-894b-4e34-be35-57f44d569591) · [Buy the bundle](https://digitalgemology.lemonsqueezy.com/checkout/buy/9170b0c0-5357-490e-b6ef-3ce4f7fcd282?checkout%5Bdiscount_code%5D=BUNDLE25) · [Get the cube free](https://digitalgemology.lemonsqueezy.com/checkout/buy/2d1ab55f-2bd6-4897-a4cd-f3320f54e99e) 3D model and faceting diagram · 49 facets · 7.64 x 7.64 mm An eight-sided cut with the same tier profile as the hexagon: a stepped crown over a three-tier pavilion. [3D files · €9.99](https://digitalgemology.lemonsqueezy.com/checkout/buy/26baac35-16bd-4143-97ba-9eeb7fd4da11) [Cutting files · €6.99](https://digitalgemology.lemonsqueezy.com/checkout/buy/390b595d-894b-4e34-be35-57f44d569591) Instant download · [Personal-use license](https://digitalgemology.com/licence) · [What is in the files](https://digitalgemology.com/cuts/octagon#buy) · [Grade it in 3D](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=octagon) ## About the Octagon Cut An eight-sided cut with the same tier profile as the hexagon: a stepped crown over a three-tier pavilion. A crisp geometric outline for modern designs and colored stones. ## Octagon Cut specifications Measured from the delivered model, not quoted from a standard. **Category** Jewelry cuts **Facets** 49 planar facets (41 + 8 girdles = 49) **Outline** Length to width 1.000 **Total depth** 61.0% of width **Table** 60.0% of width **Crown angle (main)** 39.8° **Pavilion angle (main)** 29.3° **Reference size** 7.64 x 7.64 x 4.66 mm at 2.00 ct in diamond **Volume** 113.64 mm³ **Cutting file accuracy** Every crown and pavilion facet within under 0.001° of the 3D model (average under 0.001°) **Index gear** 96 **Symmetry** 8-fold mirror-image symmetry **Tiers** 2 crown, 3 pavilion **Files** STEP, 3DM, STL, OBJ, FBX, GLB, GemCad .asc, tier table, diagram ## Face-up and profile *Face-up facet diagram of the Octagon Cut* Face-up: the crown facets, drawn from the model's own edges. *Side profile of the Octagon Cut* Profile: 61.0% total depth. ![Light Return map of the Octagon Cut in diamond: a computed render showing direct, indirect and contrast light across the face-up stone.](https://digitalgemology.com/img/cuts/octagon-lightmap.webp?v=8be5f942) Light Return map of the Octagon Cut in diamond. A computed render of the model's geometry, not a photograph. ## Cut Performance Index - Diamond **79.9** overall, 17th of 37 - Moissanite **82.2** overall, 18th of 37 - Cubic Zirconia **82.3** overall, 18th of 37 - Ruby **71.8** overall, 17th of 37 - Sapphire **71.8** overall, 17th of 37 - Emerald **67.0** overall, 16th of 37 - Amethyst **63.9** overall, 16th of 37 [See how every cut compares](https://digitalgemology.com/learn/cut-performance-index) ## How the Octagon Cut performs in seven gemstones **The Octagon Cut performs best in moissanite, where its brilliance and fire together are highest: 67 for brilliance and 94 for fire.** Its brilliance peaks in ruby and sapphire, at 78. In diamond it scores 71 for brilliance and 76 for fire, against 93 and 78 for the T73 benchmark. Its scintillation, 66, comes from its pattern of facets, so it is the same in every stone. **Brilliance, fire and scintillation of the Octagon Cut in seven gemstones, out of 100, with the T73 Round Brilliant benchmark in each** | Gemstone | Brilliance | Fire | Scintillation | | --- | --- | --- | --- | | [Diamond](https://digitalgemology.com/gemstones/diamond) | 71 (T73 benchmark 93) | 76 (T73 benchmark 78) | 66 (T73 benchmark 80) | | [Moissanite](https://digitalgemology.com/gemstones/moissanite) *Best overall* *Highest fire* | 67 (T73 benchmark 86) | 94 (T73 benchmark 97) | 66 (T73 benchmark 80) | | [Cubic Zirconia](https://digitalgemology.com/gemstones/cubic-zirconia) | 76 (T73 benchmark 98) | 80 (T73 benchmark 87) | 66 (T73 benchmark 80) | | [Ruby](https://digitalgemology.com/gemstones/ruby) *Highest brilliance* | 78 (T73 benchmark 94) | 33 (T73 benchmark 37) | 66 (T73 benchmark 80) | | [Sapphire](https://digitalgemology.com/gemstones/sapphire) *Highest brilliance* | 78 (T73 benchmark 94) | 33 (T73 benchmark 37) | 66 (T73 benchmark 80) | | [Emerald](https://digitalgemology.com/gemstones/emerald) | 69 (T73 benchmark 78) | 34 (T73 benchmark 39) | 66 (T73 benchmark 80) | | [Amethyst](https://digitalgemology.com/gemstones/amethyst) | 64 (T73 benchmark 72) | 28 (T73 benchmark 36) | 66 (T73 benchmark 80) | Score out of 100 T73 Round Brilliant, our benchmark, in the same stone **Best overall:** the highest brilliance and fire together Brilliance is the share of face-up light that the stone returns. Fire is the share of that light that splits into color. Both come from our face-up light census. Scintillation is the sparkle that the facets give as the stone moves, and we read it from its facets. They are the same figures as the [Cut Performance Wheel](https://digitalgemology.com/tools/cut-performance-wheel?cut=octagon&stone=moissanite), where you can compare the Octagon Cut with any other cut. A simulation of the geometry, not a grading report. ### Head-on reflection, critical angle and weight in each stone The same geometry behaves differently in every material. Light that meets a pavilion facet at less than the critical angle of the stone does not reflect. It passes straight out of the back and shows face-up as a window. For each stone, we measured how much of the pavilion of this model, seen face-down, is steeper than that angle. We also measured what the model weighs at its reference size. The pavilion mains of this design sit at 29.3°. A round design needs at least 40.4° in amethyst for head-on light to reflect off both sides of the pavilion and leave through the table. So it is worth making the mains steeper for ruby, sapphire, emerald, amethyst. Head-on light in amethyst: a steep facet reflects it, a shallow facet lets it out of the back. | Stone | Refractive index | Critical angle | Pavilion reflecting head-on light | Weight at this size | Verdict | | --- | --- | --- | --- | --- | --- | | [Diamond](https://digitalgemology.com/gemstones/diamond) | 2.417 | 24.4° | 100% | 2.00 ct | Holds head-on light | | [Moissanite](https://digitalgemology.com/gemstones/moissanite) | 2.648 to 2.691 | 22.2° | 100% | 1.83 ct | Holds head-on light | | [Cubic Zirconia](https://digitalgemology.com/gemstones/cubic-zirconia) | 2.15 to 2.18 | 27.7° | 100% | 3.30 ct | Holds head-on light | | [Ruby](https://digitalgemology.com/gemstones/ruby) | 1.762 to 1.770 | 34.6° | 89% | 2.27 ct | Steepen the pavilion | | [Sapphire](https://digitalgemology.com/gemstones/sapphire) | 1.762 to 1.770 | 34.6° | 89% | 2.27 ct | Steepen the pavilion | | [Emerald](https://digitalgemology.com/gemstones/emerald) | 1.577 to 1.583 | 39.4° | 89% | 1.55 ct | Steepen the pavilion | | [Amethyst](https://digitalgemology.com/gemstones/amethyst) | 1.544 to 1.553 | 40.4° | 89% | 1.51 ct | Steepen the pavilion | Head-on light, first reflection. The [3D Gemstone Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=octagon) traces the full Light Return in each of these gemstones. ## Available in… The Octagon Cut stone by stone: what each gemstone gains and loses in this cut, measured. - [Diamond](https://digitalgemology.com/gemstones/diamond/octagon) - [Moissanite](https://digitalgemology.com/gemstones/moissanite/octagon) - [Cubic Zirconia](https://digitalgemology.com/gemstones/cubic-zirconia/octagon) - [Ruby](https://digitalgemology.com/gemstones/ruby/octagon) - [Sapphire](https://digitalgemology.com/gemstones/sapphire/octagon) - [Emerald](https://digitalgemology.com/gemstones/emerald/octagon) - [Amethyst](https://digitalgemology.com/gemstones/amethyst/octagon) ![Octagon Cut 3D model](https://digitalgemology.com/img/cuts/octagon-3d.webp?v=75207f45) ## Grade the Octagon Cut in 3D Open it in the 3D Gemstone Simulator. Set its carat, color, clarity and cut grade in any of seven gemstones. Turn it under ten kinds of light, and watch its 3D gemstone report change as you go. Free, in your browser. [Open it in the Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=octagon) ## Octagon Cut: questions ### What files come with the Octagon Cut 3D model? Six formats. STEP is the exact faceted 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 49 planar facets. ### Is there a faceting diagram for the Octagon Cut? Yes. The cutting files contain a GemCad .asc design (41 + 8 girdles = 49 facets, 96 index, 8-fold mirror-image symmetry) and a printable faceting diagram. They also contain a tier table in CSV, with the angles, indices and cutting order. ### Does the Octagon Cut work in sapphire, emerald or amethyst? We measured the pavilion of this model against the critical angle of each stone. In Diamond, Moissanite, Cubic Zirconia, the whole pavilion reflects head-on light. In Ruby, Sapphire, Emerald, Amethyst, part of the pavilion lets light out of the back, so we advise a steeper pavilion. The pavilion mains of this design sit at 29.3°. A round design needs at least 40.4° in amethyst for head-on light to reflect off both sides of the pavilion and leave through the table. So it is worth making the mains steeper for ruby, sapphire, emerald, amethyst. ### How accurate is the Octagon Cut cutting file? We check it facet by facet against the 3D model that it was written from. Every crown and pavilion facet within under 0.001° 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 that you render or set. ### How big is the Octagon Cut model, and what does it weigh? The model measures 7.64 x 7.64 x 4.66 mm, which is 2.00 ct in diamond. At the same size, it 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. You can scale it uniformly to any size: the weight follows the cube of the size. Twice the size holds eight times the material, so it weighs eight times as much. ### Can I 3D print or cast the Octagon Cut model? 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. ## More jewelry cuts - [Baguette Cut](https://digitalgemology.com/cuts/baguette) - [Emerald Cut](https://digitalgemology.com/cuts/emerald-cut) - [Marquise Cut](https://digitalgemology.com/cuts/marquise) - [Oval Cut](https://digitalgemology.com/cuts/oval) - [Pear Cut](https://digitalgemology.com/cuts/pear) - [Radiant Cut](https://digitalgemology.com/cuts/radiant) - [Rectangle Cut](https://digitalgemology.com/cuts/rectangle) - [Teardrop Cut](https://digitalgemology.com/cuts/teardrop) - [Asscher Cut](https://digitalgemology.com/cuts/asscher) - [Cushion Cut](https://digitalgemology.com/cuts/cushion) - [Emerald Square Cut](https://digitalgemology.com/cuts/emerald-square) - [Princess Cut](https://digitalgemology.com/cuts/princess) - [Radiant Square Cut](https://digitalgemology.com/cuts/radiant-square) - [Square Cut](https://digitalgemology.com/cuts/square) - [Triangle Cut](https://digitalgemology.com/cuts/triangle) - [Trilliant Cut](https://digitalgemology.com/cuts/trilliant) - [Trillion Cut](https://digitalgemology.com/cuts/trillion) - [Heart Cut](https://digitalgemology.com/cuts/heart) - [Hexagon Cut](https://digitalgemology.com/cuts/hexagon) - [Portuguese Bird's Nest Cut](https://digitalgemology.com/cuts/portuguese-birds-nest) ## Get the Octagon Cut files *6 formats* *Millimeters* *Watertight* ### Octagon Cut 3D files The Octagon Cut as exact geometry: 49 planar facets, real-world scale, ready for CAD, rendering, printing and casting. - **STEP** Exact faceted solid for CAD - **3DM** Rhino, closed mesh on its own layer - **STL** Watertight mesh for printing and casting - **OBJ** Mesh for modeling and rendering - **FBX** Blender, 3ds Max, Maya, Cinema 4D, Unity, Unreal - **GLB** Web, AR and quick previews €9.99 · [Personal use](https://digitalgemology.com/licence) [Buy the 3D files](https://digitalgemology.lemonsqueezy.com/checkout/buy/26baac35-16bd-4143-97ba-9eeb7fd4da11) *GemCad* *96 index* ### Octagon Cut cutting files The Octagon Cut as a faceting design: 41 + 8 girdles = 49 facets, 96 index, 8-fold mirror-image symmetry, ready for the machine. - **.asc** GemCad design file, 96 index gear - **.csv** Tier table: angles, indices and cutting order - **Diagram** Printable faceting diagram €6.99 · [Personal use](https://digitalgemology.com/licence) [Buy the cutting files](https://digitalgemology.lemonsqueezy.com/checkout/buy/390b595d-894b-4e34-be35-57f44d569591) Save with a bundle: the Octagon Cut cutting files are also in [Faceter's Classics](https://digitalgemology.com/cuts/#bundles), 10 cuts for €22.49 until 1 December, then €29.99 (€69.90 as single files). [Buy the bundle](https://digitalgemology.lemonsqueezy.com/checkout/buy/9170b0c0-5357-490e-b6ef-3ce4f7fcd282?checkout%5Bdiscount_code%5D=BUNDLE25). Not sure the files open in your software? [Get the cube free](https://digitalgemology.lemonsqueezy.com/checkout/buy/2d1ab55f-2bd6-4897-a4cd-f3320f54e99e): the same six formats, for your email address, used only to send them ([privacy](https://digitalgemology.com/privacy#free-sample)). Questions before you buy? [Email us](mailto:support@digitalgemology.com).