---
title: "T73 Round Brilliant Demantoid: Pros, Cons and Scores"
description: "T73 Round Brilliant in demantoid: brilliance 97, fire 84, leakage 3%, 3 pros and 3 cons against the T57, from our ray-traced light census."
url: https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant
image: https://digitalgemology.com/img/stone-cuts/t73-round-brilliant-demantoid-og.jpg?v=c7ac934c
---

> Markdown copy of https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant. 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

# T73 Round Brilliant Demantoid: more facets, more sparkle

**Buy (instant download, personal-use license):** [T73 Round Brilliant Cut 3D files, €9.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/ef4dd7c5-5809-4458-9eff-1beb80ed52c0) · [T73 Round Brilliant Cut cutting files, €6.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/44ee6a27-8125-4940-b84c-6c368746df74) · [Buy the bundle](https://digitalgemology.lemonsqueezy.com/checkout/buy/e5c79ed5-97ce-4c62-8dbe-3a172c6245ba?checkout%5Bdiscount_code%5D=BUNDLE25) · [Get the cube free](https://digitalgemology.lemonsqueezy.com/checkout/buy/2d1ab55f-2bd6-4897-a4cd-f3320f54e99e)

Brilliance 97 · Fire 84 · Scintillation 80 · in our census, where the T57 scores 97 · 84 · 72 in demantoid

How the T73 Round Brilliant handles light in demantoid, measured: brilliance 97, fire 84 and 3% leakage, set against the T57 in the same stone and against the same cut in diamond.

[Get the files](https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant#buy) [Open it in the Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=t73-round-brilliant&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 T73 Round Brilliant in demantoid, face-up, from our own tracer at refractive index 1.881. Red, green and blue return light to the eye; gray leaks.

## T73 Round Brilliant 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 T73 Round Brilliant in demantoid live.

The T73 Round Brilliant has 73 facets and a total depth of 61.7% of its width; its pavilion mains sit at 40.8°. In demantoid, the census returns 97 of 100 for brilliance and 84 for fire, against 97 and 84 for the T57, our benchmark, in the same stone; the same T73 Round Brilliant in diamond reads 93 and 78.

## Is demantoid good in a T73? Pros and cons, measured

### Pros

- [More facets, more sparkle](https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant#pro-scint) 80 vs 72
- [More fire in demantoid than in diamond](https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant#pro-fire) 84 vs 78
- [Brighter in demantoid than in diamond](https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant#pro-brilliance) 97 vs 93

### Cons

- [Loses more light when tilted than in diamond](https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant#con-tiltStab) 79 vs 92
- [Heavier than the same cut in diamond](https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant#con-weight) 1.10 vs 1.01 ct
- [Faces up smaller for its weight](https://digitalgemology.com/gemstones/demantoid/t73-round-brilliant#con-faceup) 100 vs 107

Compared with the T57 Round Brilliant in demantoid and with the T73 Round Brilliant 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 T57

At a glance: the T73 Round Brilliant in demantoid (white) against the T57 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 T57 Round Brilliant in demantoid: ahead on 3, level on 4, behind on 1.

- Global 90, the comparison 89, difference +1
- Brilliance 97, the comparison 97, difference 0
- Fire 84, the comparison 84, difference 0
- Scintillation 80, the comparison 72, difference +8
- Spread 100, the comparison 101, difference −1
- Symmetry 100, the comparison 100, difference 0
- Shape-norm 104, the comparison 104, difference 0
- Tilt 79, the comparison 78, difference +1

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=t73-round-brilliant&stone=demantoid); these are the same census figures as our [Cut Performance Index](https://digitalgemology.com/learn/cut-performance-index).

## What the T73 Round Brilliant gains in demantoid

### More facets, more sparkle

**Scintillation 80** against 72 for the T57 Round Brilliant in demantoid: 8 points higher

Scintillation follows the number of facets the stone shows: 100 × (1 − e^(−facets / 45)). The T73 Round Brilliant has 73 facets and the T57 57, so 80 against 72. It depends on the geometry alone, so it is the same in every stone.

*Facet diagram of the T73 Round Brilliant: its crown, seen face-up, 73 facets in all*

T73 Round Brilliant · 73 facets · Scintillation 80

*Facet diagram of the T57 Round Brilliant: its crown, seen face-up, 57 facets in all*

T57 Round Brilliant · 57 facets · Scintillation 72

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.

[Try it yourself: Compare the Scintillation spoke in the Cut Performance Wheel](https://digitalgemology.com/tools/cut-performance-wheel?cut=t73-round-brilliant&stone=demantoid&vs=t57-round-brilliant)

### More fire in demantoid than in diamond

**Fire 84** against 78 for the T73 Round Brilliant in diamond: 6 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 T73 Round Brilliant reads 84 against 78 for the same cut in diamond. 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=t73-round-brilliant&stone=demantoid&ct=1.00&view=up&lighting=sun&turn=0): the T73 Round Brilliant 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=t73-round-brilliant&stone=demantoid&ct=1.00&view=up&lighting=sun&turn=0)

### Brighter in demantoid than in diamond

**Brilliance 97** against 93 for the T73 Round Brilliant in diamond: 4 points higher

The same cut in diamond returns 93. Demantoid bends light less than diamond: its critical angle is 32.1°, diamond's 24.4°, so a pavilion facet has to be steeper before light reflects off it rather than passing out. The T73 Round Brilliant's pavilion returns more of demantoid's light than of diamond's, as the two maps show.

T73 Round Brilliant in demantoid · Brilliance 97

T73 Round Brilliant in diamond · Brilliance 93

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.

[Try it yourself: Open this Light Return map in the simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=t73-round-brilliant&stone=demantoid&ct=1.00&view=up&map=1&turn=0)

## What the T73 Round Brilliant gives up in demantoid

### Loses more light when tilted than in diamond

**Tilt 79** against 92 for the T73 Round Brilliant in diamond: 13 points lower

Tilt is how much of its face-up brilliance a stone keeps when the census tilts it 20° about its long axis, with 2,200 rays. The T73 Round Brilliant keeps 79 against 92 for the same cut in diamond. The tilt strips below show the maps at 0°, 10°, 20° and 30°, with each picture's own leak share under it.

T73 Round Brilliant in demantoid · Tilt 79

0° · 1% leak

10° · 6% leak

20° · 17% leak

30° · 29% leak

T73 Round Brilliant in diamond · Tilt 92

0° · 4% leak

10° · 2% leak

20° · 9% leak

30° · 14% leak

Tilt is how much of its own face-up light a stone keeps when tilted. 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-M5](https://digitalgemology.com/gemstones/demantoid/dg-m5) reads 89 for tilt in demantoid, the best of the cuts we score there.

[Try it yourself: Compare the Tilt spoke in the Cut Performance Wheel](https://digitalgemology.com/tools/cut-performance-wheel?cut=t73-round-brilliant&stone=demantoid&vs=t73-round-brilliant&vsstone=diamond)

### Heavier than the same cut in diamond

**1.10 ct** at 6.5 mm, against 1.01 ct for the same cut in diamond (+9%)

Weight follows specific gravity: 3.85 for demantoid against 3.52 for diamond, so the same model at the same size weighs 1.10 ct here and 1.01 ct in diamond, 6.5 mm across. Nothing about the light changes with it.

*Weight of a 6.5 mm T73 Round Brilliant: 1.10 ct in demantoid, 1.01 ct in diamond*

A T73 Round Brilliant 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.

[Try it yourself: Weights in every gemstone on the T73 Round Brilliant page](https://digitalgemology.com/cuts/t73-round-brilliant#stones)

### Faces up smaller for its weight

**Face-up size 100** against 107 for the T57 Round Brilliant in demantoid (T73 = 100): 7% less face-up area for the same weight

Face-up size is the outline's area per carat, measured from each model (T73 = 100): 100 for the T73 Round Brilliant against 107 for the T57. 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 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

*Face-up outline of the T57 Round Brilliant at 1.00 ct in demantoid: 6.49 mm, drawn to scale*

T57 Round Brilliant · 6.49 mm at 1.00 ct · Face-up size 107

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=t73-round-brilliant&stone=demantoid&ct=1.00&view=up&lighting=studio&turn=0)

## Our verdict on the T73 Round Brilliant in demantoid

Pick the T73 Round Brilliant in demantoid for this: it has more facets to sparkle with, shows more fire than in diamond and returns more light than in diamond. The catch: it loses more light when tilted than in diamond, weighs more than in diamond and faces up smaller for its weight.

If that catch matters more to you, [the DG-M5](https://digitalgemology.com/gemstones/demantoid/dg-m5) reads 89 for tilt 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 T73 Round Brilliant model we traced.

## T73 Round Brilliant Demantoid: questions

### Is the T73 a good cut for demantoid?

In our census the T73 Round Brilliant returns 97 of 100 for brilliance and 84 for fire in demantoid, against 97 and 84 for the T57 in the same stone. Against that round and against the same cut in diamond it has 3 pros and 3 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 T73 Round Brilliant's pavilion mains sit at 40.8°.

### How much does a T73 weigh in demantoid?

At 6.5 mm across, 1.10 ct in demantoid, against 1.01 ct for the same cut in diamond (+9%): demantoid's specific gravity is 3.85, diamond's 3.52.

### Can I see the T73 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 T73 Round Brilliant Cut files

*6 formats* *Millimeters* *Watertight*

### T73 Round Brilliant Cut 3D files

The T73 Round Brilliant Cut as exact geometry: 73 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/ef4dd7c5-5809-4458-9eff-1beb80ed52c0)

*GemCad* *96 index*

### T73 Round Brilliant Cut cutting files

The T73 Round Brilliant Cut as a faceting design: 57 + 16 girdles = 73 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/44ee6a27-8125-4940-b84c-6c368746df74)

Save with a bundle: the T73 Round Brilliant Cut 3D files are also in [Jewelry Essentials 3D](https://digitalgemology.com/cuts/#bundles), 10 cuts for €29.99 until 1 December, then €39.99 (€99.90 as single files). [Buy the bundle](https://digitalgemology.lemonsqueezy.com/checkout/buy/e5c79ed5-97ce-4c62-8dbe-3a172c6245ba?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).

## More gemstones and cuts

[Demantoid: optical properties and the top ten cuts](https://digitalgemology.com/gemstones/demantoid) · [The T73 Round Brilliant: specifications, model and files](https://digitalgemology.com/cuts/t73-round-brilliant)

### Other cuts in demantoid

- [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)
- [Old Single Cut](https://digitalgemology.com/gemstones/demantoid/old-single)
- [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 T73 Round Brilliant in other gemstones

- [Diamond](https://digitalgemology.com/gemstones/diamond/t73-round-brilliant)
- [Moissanite](https://digitalgemology.com/gemstones/moissanite/t73-round-brilliant)
- [Cubic Zirconia](https://digitalgemology.com/gemstones/cubic-zirconia/t73-round-brilliant)
- [Ruby](https://digitalgemology.com/gemstones/ruby/t73-round-brilliant)
- [Sapphire](https://digitalgemology.com/gemstones/sapphire/t73-round-brilliant)
- [Emerald](https://digitalgemology.com/gemstones/emerald/t73-round-brilliant)
- [Amethyst](https://digitalgemology.com/gemstones/amethyst/t73-round-brilliant)
- [Topaz](https://digitalgemology.com/gemstones/topaz/t73-round-brilliant)
- [Spinel](https://digitalgemology.com/gemstones/spinel/t73-round-brilliant)
- [Zircon](https://digitalgemology.com/gemstones/zircon/t73-round-brilliant)
- [Tourmaline](https://digitalgemology.com/gemstones/tourmaline/t73-round-brilliant)
- [Peridot](https://digitalgemology.com/gemstones/peridot/t73-round-brilliant)
- [Tanzanite](https://digitalgemology.com/gemstones/tanzanite/t73-round-brilliant)
- [YAG](https://digitalgemology.com/gemstones/yag/t73-round-brilliant)
- [Pyrope](https://digitalgemology.com/gemstones/pyrope/t73-round-brilliant)
- [Almandine](https://digitalgemology.com/gemstones/almandine/t73-round-brilliant)
- [Spessartine](https://digitalgemology.com/gemstones/spessartine/t73-round-brilliant)
- [Grossular](https://digitalgemology.com/gemstones/grossular/t73-round-brilliant)
- [Chrysoberyl](https://digitalgemology.com/gemstones/chrysoberyl/t73-round-brilliant)
- [Kunzite](https://digitalgemology.com/gemstones/kunzite/t73-round-brilliant)
- [Iolite](https://digitalgemology.com/gemstones/iolite/t73-round-brilliant)
- [Morganite](https://digitalgemology.com/gemstones/morganite/t73-round-brilliant)
- [GGG](https://digitalgemology.com/gemstones/ggg/t73-round-brilliant)
- [Strontium titanate](https://digitalgemology.com/gemstones/strontium-titanate/t73-round-brilliant)
- [Synthetic rutile](https://digitalgemology.com/gemstones/synthetic-rutile/t73-round-brilliant)