--- title: "Old Single Cut Demantoid: Pros, Cons and Scores" description: "Old Single Cut in demantoid: brilliance 49, fire 91, leakage 42%, 1 pro and 4 cons against the T73, from our ray-traced light census." url: https://digitalgemology.com/gemstones/demantoid/old-single image: https://digitalgemology.com/img/stone-cuts/old-single-demantoid-og.jpg?v=566e7850 --- > Markdown copy of https://digitalgemology.com/gemstones/demantoid/old-single. 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 # Old Single Cut Demantoid: more fire than the T73 in demantoid **Buy (instant download, personal-use license):** [Old Single Cut 3D files, €9.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/3676049d-d816-4345-abd1-6b493531442a) · [Old Single Cut cutting files, €6.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/8370cbbe-94b3-4fca-9136-d3396779812e) · [Buy the bundle](https://digitalgemology.lemonsqueezy.com/checkout/buy/dcf2c236-6e04-4292-8040-9d21ac6446d1?checkout%5Bdiscount_code%5D=HISTORIC25) · [Get the cube free](https://digitalgemology.lemonsqueezy.com/checkout/buy/2d1ab55f-2bd6-4897-a4cd-f3320f54e99e) Brilliance 49 · Fire 91 · Scintillation 44 · in our census, where the T73 scores 97 · 84 · 80 in demantoid How the Old Single Cut handles light in demantoid, measured: brilliance 49, fire 91 and 42% leakage, set against the T73 in the same stone and against the same cut in diamond. [Get the files](https://digitalgemology.com/gemstones/demantoid/old-single#buy) [Open it in the Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-single&stone=demantoid&ct=1.00&view=angle&lighting=studio&turn=0) [All cuts in demantoid](https://digitalgemology.com/gemstones/demantoid) Light Return map of the Old Single Cut in demantoid, face-up, from our own tracer at refractive index 1.881. Red, green and blue return light to the eye; gray leaks. ## Old Single Cut Demantoid Demantoid has a refractive index of 1.881 to 1.888 and a dispersion of 0.057. Its critical angle, from the low end of that range, is 32.1°, so a round design needs a pavilion of at least 37.0° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 1.885, the midpoint of the published range, and a fire spread of 0.049, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 1.881, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the Old Single Cut in demantoid live. The Old Single Cut has 26 facets, a table of 57.5% of its width and a total depth of 67.5% of its width; its pavilion mains sit at 48.5°. In demantoid, the census returns 49 of 100 for brilliance and 91 for fire, against 97 and 84 for the T73, our benchmark, in the same stone; the same Old Single Cut in diamond reads 72 and 84. ## Is demantoid good in an Old Single? Pros and cons, measured ### Pros - [More fire than the T73 in demantoid](https://digitalgemology.com/gemstones/demantoid/old-single#pro-fire) 91 vs 84 ### Cons - [Returns less light than the T73 in demantoid](https://digitalgemology.com/gemstones/demantoid/old-single#con-brilliance) 49 vs 97 - [Leaks more light than the T73 in demantoid](https://digitalgemology.com/gemstones/demantoid/old-single#con-leak) 42 vs 3 - [Fewer facets, less sparkle](https://digitalgemology.com/gemstones/demantoid/old-single#con-scint) 44 vs 80 - [Faces up smaller for its weight](https://digitalgemology.com/gemstones/demantoid/old-single#con-faceup) 90 vs 100 Compared with the T73 Round Brilliant in demantoid and with the Old Single Cut in diamond. A difference counts from 3 points (Brilliance, Fire, Tilt, Leakage), 5 (Scintillation, Symmetry), 4% (face-up size per carat) or 5% (weight); Tilt counts as a pro only for a stone within 5 points of the brilliance it is compared with. [How we measure](https://digitalgemology.com/about/how-we-measure). ## All eight scores against the T73 At a glance: the Old Single Cut in demantoid (white) against the T73 Round Brilliant in demantoid (dashed): solid white where it reaches further, hatched where it falls short. Each pro and con is explained, with pictures, below. Against the T73 Round Brilliant in demantoid: ahead on 2, level on 1, behind on 5. - Global 71, the comparison 90, difference −19 - Brilliance 49, the comparison 97, difference −48 - Fire 91, the comparison 84, difference +7 - Scintillation 44, the comparison 80, difference −36 - Spread 97, the comparison 100, difference −3 - Symmetry 100, the comparison 100, difference 0 - Shape-norm 52, the comparison 104, difference −52 - Tilt 100, the comparison 79, difference +21 Face-up light census, a different measure from the Cut Grading Tool; Spread and Shape-norm above 100 sit on the ring. Spread is the census's estimate from depth alone; the face-up size in the pros and cons is measured from each model's outline. [Open it in the Cut Performance Wheel](https://digitalgemology.com/tools/cut-performance-wheel?cut=old-single&stone=demantoid); these are the same census figures as our [Cut Performance Index](https://digitalgemology.com/learn/cut-performance-index). ## What the Old Single Cut gains in demantoid ### More fire than the T73 in demantoid **Fire 91** against 84 for the T73 Round Brilliant in demantoid: 7 points higher Fire is the share of the returned light that splits into color at the exit facet: the census traces each exit again at the refractive index minus and plus the fire spread (0.049 in demantoid) and counts a ray as fire when the two directions differ by more than 0.6°. The Old Single Cut reads 91 against 84 for the T73 in demantoid. The figure is the census's; the 3D Gemstone Simulator renders demantoid's fire live. The fire figure is the census's, traced at the refractive index minus and plus the fire spread. [See the fire in the 3D Gemstone Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-single&stone=demantoid&ct=1.00&view=up&lighting=sun&turn=0): the Old Single Cut in demantoid under the sunny-day lighting. [Try it yourself: See the fire in the 3D Gemstone Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-single&stone=demantoid&ct=1.00&view=up&lighting=sun&turn=0) ## What the Old Single Cut gives up in demantoid ### Returns less light than the T73 in demantoid **Brilliance 49** against 97 for the T73 Round Brilliant in demantoid: 48 points lower Brilliance is the share of the 3,200 census rays that enter the stone and come back out of the crown towards the viewer. In demantoid, whose critical angle is 32.1°, the Old Single Cut returns 49 of 100 and the T73 97. The Old Single Cut's pavilion mains sit at 48.5°, the T73's at 40.8°. The maps below show where each stone's light returns from and where it leaks. Old Single Cut in demantoid · Brilliance 49 T73 Round Brilliant in demantoid · Brilliance 97 Red, green and blue = light returning to the eye; gray = leakage, light that leaves heading down or stays inside. This is the head-on view; the Brilliance score averages a wider cone of light, so the score can differ from what one picture shows. **What helps:** [the DG-Broken Hearts and Arrows](https://digitalgemology.com/gemstones/demantoid/dg-broken-hearts-and-arrows) reads 97 for brilliance in demantoid, the best of the cuts we score there. [Try it yourself: Open this Light Return map in the simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-single&stone=demantoid&ct=1.00&view=up&map=1&turn=0) ### Leaks more light than the T73 in demantoid **Leakage 42** against 3 for the T73 Round Brilliant in demantoid: 39 points higher Leakage is the share of the census rays that enter the stone and leave through the pavilion, or through the crown heading down. The Old Single Cut leaks 42% in demantoid against 3% for the T73 in demantoid. Grey in the maps below is leaking light; the share under each picture is that picture's own. Old Single Cut in demantoid · Leakage 42 0° · 36% leak 10° · 42% leak 20° · 41% leak 30° · 42% leak T73 Round Brilliant in demantoid · Leakage 3 0° · 1% leak 10° · 6% leak 20° · 17% leak 30° · 29% leak Each frame is the Light Return map with the stone tilted away from you by the angle shown; gray is leakage. The share under each frame is that picture's own. **What helps:** [the DG-Broken Hearts and Arrows](https://digitalgemology.com/gemstones/demantoid/dg-broken-hearts-and-arrows) reads 3% for leakage in demantoid, the best of the cuts we score there. [Try it yourself: Tilt it yourself in the simulator's light map](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-single&stone=demantoid&ct=1.00&view=up&map=1&turn=0) ### Fewer facets, less sparkle **Scintillation 44** against 80 for the T73 Round Brilliant in demantoid: 36 points lower Scintillation follows the number of facets the stone shows: 100 × (1 − e^(−facets / 45)). The Old Single Cut has 26 facets and the T73 73, so 44 against 80. It depends on the geometry alone, so it is the same in every stone. *Facet diagram of the Old Single Cut: its crown, seen face-up, 26 facets in all* Old Single Cut · 26 facets · Scintillation 44 *Facet diagram of the T73 Round Brilliant: its crown, seen face-up, 73 facets in all* T73 Round Brilliant · 73 facets · Scintillation 80 Scintillation follows the number of facets: more facets, more and smaller flashes as the stone moves. Compare the facet counts under the drawings; each drawing shows only the crown. Drawn from each cut's own model. **What helps:** [the DG-Miliano](https://digitalgemology.com/gemstones/demantoid/dg-miliano) reads 98 for scintillation in demantoid, the best of the cuts we score there. [Try it yourself: Compare the Scintillation spoke in the Cut Performance Wheel](https://digitalgemology.com/tools/cut-performance-wheel?cut=old-single&stone=demantoid) ### Faces up smaller for its weight **Face-up size 90** against 100 for the T73 Round Brilliant in demantoid (T73 = 100): 10% less face-up area for the same weight Face-up size is the outline's area per carat, measured from each model (T73 = 100): 90 for the Old Single Cut against 100 for the T73. The same volume spread over a longer or shallower outline shows more face for the weight; it is the same in every stone, because specific gravity scales every cut alike. *Face-up outline of the Old Single Cut at 1.00 ct in demantoid: 6.20 mm, drawn to scale* Old Single Cut · 6.20 mm at 1.00 ct · Face-up size 90 *Face-up outline of the T73 Round Brilliant at 1.00 ct in demantoid: 6.29 mm, drawn to scale* T73 Round Brilliant · 6.29 mm at 1.00 ct · Face-up size 100 Both stones weigh 1.00 ct in demantoid and are drawn to the same scale in millimeters, from each cut's own model. Face-up size is the outline's area per carat, with the T73 at 100: a deeper stone, or a rounder outline, spreads less area for its weight. **What helps:** [the Marquise Cut](https://digitalgemology.com/gemstones/demantoid/marquise) reads 121 for face-up size in demantoid, the best of the cuts we score there. [Try it yourself: See its size at 1.00 ct in demantoid in the 3D Gemstone Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=old-single&stone=demantoid&ct=1.00&view=up&lighting=studio&turn=0) ## Our verdict on the Old Single Cut in demantoid Pick the Old Single Cut in demantoid for this: it shows more fire than the T73. The catch: it returns less light than the T73, leaks more light than the T73, has fewer facets to sparkle with and faces up smaller for its weight. If that catch matters more to you, [the DG-Broken Hearts and Arrows](https://digitalgemology.com/gemstones/demantoid/dg-broken-hearts-and-arrows) reads 97 for brilliance in demantoid, the best of the cuts we score there. Every figure on this page is from our light census, traced at one refractive index: a simulation of the geometry, not a grading report. The 3D files and cutting files below are the same Old Single Cut model we traced. ## Old Single Cut Demantoid: questions ### Is the Old Single a good cut for demantoid? In our census the Old Single Cut returns 49 of 100 for brilliance and 91 for fire in demantoid, against 97 and 84 for the T73 in the same stone. Against that round and against the same cut in diamond it has 1 pro and 4 cons by our thresholds; the summary above names them. ### What pavilion angle does demantoid need? At least 37.0° for a round design: demantoid's critical angle is 32.1°, from the low end of its refractive index range, and head-on light has to reflect off both sides of the pavilion and leave through the table. The Old Single Cut's pavilion mains sit at 48.5°. ### How much does a Old Single weigh in demantoid? At 6.5 mm across, 1.15 ct in demantoid, against 1.05 ct for the same cut in diamond (+9%): demantoid's specific gravity is 3.85, diamond's 3.52. ### Can I see the Old Single in demantoid in 3D? Yes: the 3D Gemstone Simulator renders it live, with demantoid's own refractive index and dispersion. Demantoid is traced by the same light census as the other gemstones, with its refractive index and fire spread derived from published values, so its scores are on the same scale; the pictures here are our Light Return tracer, and the Cut Performance Wheel sets it against any other cut and stone. ## Get the Old Single Cut files *6 formats* *Millimeters* *Watertight* ### Old Single Cut 3D files The Old Single Cut as exact geometry: 26 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/3676049d-d816-4345-abd1-6b493531442a) *GemCad* *96 index* ### Old Single Cut cutting files The Old Single Cut as a faceting design: 18 + 8 girdles = 26 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/8370cbbe-94b3-4fca-9136-d3396779812e) Save with a bundle: the Old Single Cut 3D and cutting files are also in [Historic Cuts Complete](https://digitalgemology.com/cuts/#bundles), 6 cuts for €29.99 until 1 December, then €39.99 (€101.88 as single files). [Buy the bundle](https://digitalgemology.lemonsqueezy.com/checkout/buy/dcf2c236-6e04-4292-8040-9d21ac6446d1?checkout%5Bdiscount_code%5D=HISTORIC25). 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). ## More gemstones and cuts [Demantoid: optical properties and the top ten cuts](https://digitalgemology.com/gemstones/demantoid) · [The Old Single Cut: specifications, model and files](https://digitalgemology.com/cuts/old-single) ### Other cuts in demantoid - [T73 Round Brilliant](https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant) - [T105 Round Brilliant](https://digitalgemology.com/gemstones/demantoid/t105-round-brilliant) - [DG-Vitruvio](https://digitalgemology.com/gemstones/demantoid/dg-vitruvio) - [DG-Anteros](https://digitalgemology.com/gemstones/demantoid/dg-anteros) - [DG-Broken Hearts and Arrows](https://digitalgemology.com/gemstones/demantoid/dg-broken-hearts-and-arrows) - [Baguette Cut](https://digitalgemology.com/gemstones/demantoid/baguette) - [Emerald Cut](https://digitalgemology.com/gemstones/demantoid/emerald-cut) - [Marquise Cut](https://digitalgemology.com/gemstones/demantoid/marquise) - [Oval Cut](https://digitalgemology.com/gemstones/demantoid/oval) - [Pear Cut](https://digitalgemology.com/gemstones/demantoid/pear) - [Radiant Cut](https://digitalgemology.com/gemstones/demantoid/radiant) - [Rectangle Cut](https://digitalgemology.com/gemstones/demantoid/rectangle) - [Teardrop Cut](https://digitalgemology.com/gemstones/demantoid/teardrop) - [Asscher Cut](https://digitalgemology.com/gemstones/demantoid/asscher) - [Cushion Cut](https://digitalgemology.com/gemstones/demantoid/cushion) - [Emerald Square Cut](https://digitalgemology.com/gemstones/demantoid/emerald-square) - [Princess Cut](https://digitalgemology.com/gemstones/demantoid/princess) - [Radiant Square Cut](https://digitalgemology.com/gemstones/demantoid/radiant-square) - [Square Cut](https://digitalgemology.com/gemstones/demantoid/square) - [Triangle Cut](https://digitalgemology.com/gemstones/demantoid/triangle) - [Trilliant Cut](https://digitalgemology.com/gemstones/demantoid/trilliant) - [Trillion Cut](https://digitalgemology.com/gemstones/demantoid/trillion) - [Hexagon Cut](https://digitalgemology.com/gemstones/demantoid/hexagon) - [Octagon Cut](https://digitalgemology.com/gemstones/demantoid/octagon) - [Portuguese Bird's Nest Cut](https://digitalgemology.com/gemstones/demantoid/portuguese-birds-nest) - [Mazarin Cut](https://digitalgemology.com/gemstones/demantoid/mazarin) - [Peruzzi Cut](https://digitalgemology.com/gemstones/demantoid/peruzzi) - [Old Mine Cut](https://digitalgemology.com/gemstones/demantoid/old-mine) - [Old European Cut](https://digitalgemology.com/gemstones/demantoid/old-european) - [T57 Round Brilliant](https://digitalgemology.com/gemstones/demantoid/t57-round-brilliant) - [DG-M5](https://digitalgemology.com/gemstones/demantoid/dg-m5) - [DG-Miliano](https://digitalgemology.com/gemstones/demantoid/dg-miliano) - [DG-Rafaello](https://digitalgemology.com/gemstones/demantoid/dg-rafaello) - [DG-Bowtie](https://digitalgemology.com/gemstones/demantoid/dg-bowtie) - [DG-Elongated Hexagon](https://digitalgemology.com/gemstones/demantoid/dg-elongated-hexagon) - [DG-Octagonal Kite](https://digitalgemology.com/gemstones/demantoid/dg-octagonal-kite) ### The Old Single Cut in other gemstones - [Diamond](https://digitalgemology.com/gemstones/diamond/old-single) - [Moissanite](https://digitalgemology.com/gemstones/moissanite/old-single) - [Cubic Zirconia](https://digitalgemology.com/gemstones/cubic-zirconia/old-single) - [Sapphire](https://digitalgemology.com/gemstones/sapphire/old-single) - [Ruby](https://digitalgemology.com/gemstones/ruby/old-single) - [Emerald](https://digitalgemology.com/gemstones/emerald/old-single) - [Amethyst](https://digitalgemology.com/gemstones/amethyst/old-single) - [Topaz](https://digitalgemology.com/gemstones/topaz/old-single) - [Spinel](https://digitalgemology.com/gemstones/spinel/old-single) - [Zircon](https://digitalgemology.com/gemstones/zircon/old-single) - [Tourmaline](https://digitalgemology.com/gemstones/tourmaline/old-single) - [Peridot](https://digitalgemology.com/gemstones/peridot/old-single) - [Tanzanite](https://digitalgemology.com/gemstones/tanzanite/old-single) - [YAG](https://digitalgemology.com/gemstones/yag/old-single) - [Pyrope](https://digitalgemology.com/gemstones/pyrope/old-single) - [Almandine](https://digitalgemology.com/gemstones/almandine/old-single) - [Spessartine](https://digitalgemology.com/gemstones/spessartine/old-single) - [Grossular](https://digitalgemology.com/gemstones/grossular/old-single) - [Chrysoberyl](https://digitalgemology.com/gemstones/chrysoberyl/old-single) - [Kunzite](https://digitalgemology.com/gemstones/kunzite/old-single) - [Iolite](https://digitalgemology.com/gemstones/iolite/old-single) - [Morganite](https://digitalgemology.com/gemstones/morganite/old-single) - [GGG](https://digitalgemology.com/gemstones/ggg/old-single) - [Strontium titanate](https://digitalgemology.com/gemstones/strontium-titanate/old-single) - [Synthetic rutile](https://digitalgemology.com/gemstones/synthetic-rutile/old-single)