T73 Round Brilliant Moissanite: the modern round, with fire diamond cannot match

Brilliance 86 · Fire 97 · Scintillation 80 · in our census, where the T57 scores 85 · 98 · 72 in moissanite

Our benchmark round, cut in moissanite: much more fire than in diamond, a little less light, and the sparkle its girdle band adds over the T57.

See it in the simulatorGet the files
The T73 Round Brilliant in moissanite, rendered at an angle in our 3D Gemstone Simulator under studio light
Rendered in our 3D Gemstone Simulator from the T73 Round Brilliant model, 1.00 ct, studio light.

T73 Round Brilliant Moissanite

The T73 is the T57's plan of 57 facets with sixteen girdle facets added, 73 in all, on the same 1919 proportions. This is how most round brilliants are finished today.

On every other moissanite page the T73 is the round we compare against. Here it is the subject, so its round baseline is the T57, the knife-edge plan it grew from; the other comparison is the T73 in diamond.

Against the T57 in moissanite it is level on light, fire and tilt and ahead on sparkle. Against diamond it makes the usual moissanite trade: more colour, less light.

Is moissanite good in a round brilliant? T73 pros and cons

Pros

Cons

Compared with the T57 Round Brilliant in moissanite and with the T73 Round Brilliant in diamond. A difference counts from 3 points (Brilliance, Fire, Tilt, Leakage), 5 (Scintillation, Symmetry), 2 (Spread) 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.

All eight scores against the T57

At a glance: the T73 Round Brilliant in moissanite (white) against the T57 Round Brilliant in moissanite (dashed): solid white where it reaches further, hatched where it falls short. Each pro and con is explained, with pictures, below.

Performance wheel: T73 Round Brilliant in moissanite, against the T57 Round Brilliant in moissanite as an outline. Solid white marks where it reaches further, hatching where it falls short. The scores are listed below.50100Global+1Brilliance+1Fire−1Scintillation+8Spread−1Symmetry0Shape-norm+1Tilt+1

Against the T57 Round Brilliant in moissanite: ahead on 5, level on 1, behind on 2.

  • Global91, the comparison 90, difference +1
  • Brilliance86, the comparison 85, difference +1
  • Fire97, the comparison 98, difference −1
  • Scintillation80, the comparison 72, difference +8
  • Spread100, the comparison 101, difference −1
  • Symmetry100, the comparison 100, difference 0
  • Shape-norm93, the comparison 92, difference +1
  • Tilt94, the comparison 93, difference +1
Face-up light census, a different measure from the Cut Grading Tool; Spread and Shape-norm above 100 sit on the ring.
Open it in the Cut Performance Wheel

What moissanite gains in a T73

Far more fire than a diamond T73

Fire 97 against 78 for the T73 Round Brilliant in diamond: 19 points higher

Same model, same light, two materials: the only change between the renders is dispersion, 0.104 in moissanite against diamond's 0.044, and it lifts fire from 78 to 97.

T73 round brilliant in moissanite face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 97)

T73 Round Brilliant in moissanite · Fire 97

T73 round brilliant in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 78)

T73 Round Brilliant in diamond · Fire 78

Look at the coloured flashes: those are fire. Same light, same size, same face-up angle; rendered by our 3D Gemstone Simulator from each cut's own model.

Try it yourself: See the fire in the 3D Gemstone Simulator

Lighter than a diamond T73

0.92 ct at 6.5 mm, against 1.01 ct for the same cut in diamond (−9%)

Moissanite is the less dense stone, so a 6.5 mm T73 sits lighter in its setting than its diamond twin.

Moissanite0.92 ctDiamond1.01 ct
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 all seven gemstones on the T73 Round Brilliant page

More sparkle than the T57

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

The girdle band is all that separates the two plans, and our scintillation score counts its sixteen facets: 80 here, 72 for the T57. Whether a polished girdle adds visible sparkle face-up is not something we compute.

T73 Round Brilliant · 73 facets · Scintillation 80

T57 Round Brilliant · 57 facets · Scintillation 72

Scintillation follows the number of facets: more facets, more and smaller flashes as the stone moves. Count the facets in each crown. Drawn from each cut's own model.

Try it yourself: Compare the Scintillation spoke in the Cut Performance Wheel

The catch with a T73 moissanite

Less light than in diamond

Brilliance 86 against 93 for the T73 Round Brilliant in diamond: 7 points lower

These proportions were worked out for diamond. In the face-up Light Return maps the moissanite stone carries more grey than the diamond one, and the census agrees: 86 against 93.

T73 round brilliant in moissanite face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 86)

T73 Round Brilliant in moissanite · Brilliance 86

T73 round brilliant in diamond face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 93)

T73 Round Brilliant in diamond · Brilliance 93

Red, green and blue = light returning to the eye; grey = light leaving through the pavilion. 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: DG-Anteros Moissanite keeps this facet plan and re-solves the angles for moissanite: Brilliance 92. DG-M5 Moissanite returns 98.

Try it yourself: Open this Light Return map in the simulator

More leakage than in diamond

Leakage 7 against 2 for the T73 Round Brilliant in diamond: 5 points higher

7% of the light leaves through the pavilion in moissanite, 2% in diamond. In both tilt strips the grey thins at 10° and grows to its most at 30°, and at every angle the moissanite strip shows at least as much grey as the diamond's.

T73 Round Brilliant in moissanite · Leakage 7

T73 round brilliant in moissanite tilted 0 degrees: Light Return map, 10% of the face leaking0° · 10% leak
T73 round brilliant in moissanite tilted 10 degrees: Light Return map, 6% of the face leaking10° · 6% leak
T73 round brilliant in moissanite tilted 20 degrees: Light Return map, 10% of the face leaking20° · 10% leak
T73 round brilliant in moissanite tilted 30 degrees: Light Return map, 15% of the face leaking30° · 15% leak

T73 Round Brilliant in diamond · Leakage 2

T73 round brilliant in diamond tilted 0 degrees: Light Return map, 4% of the face leaking0° · 4% leak
T73 round brilliant in diamond tilted 10 degrees: Light Return map, 2% of the face leaking10° · 2% leak
T73 round brilliant in diamond tilted 20 degrees: Light Return map, 9% of the face leaking20° · 9% leak
T73 round brilliant in diamond tilted 30 degrees: Light Return map, 14% of the face leaking30° · 14% leak
Each frame is the Light Return map with the stone tilted away from you by the angle shown; grey is light leaving through the pavilion. The share under each frame is that picture's own.

What helps: At 40.75° the pavilion already clears moissanite's guide minimum of 39.5°, so steepening is not the fix. DG-Anteros, on the same plan, leaks 3%.

Try it yourself: Tilt it yourself in the simulator's light map

Who a T73 moissanite suits

Choose the T73 for a round moissanite that a setter and a polisher will recognise, with a girdle that can be seated. Both its cons are against diamond, and its fire sits near the top of our scale.

For more light from the same facet plan, DG-Anteros Moissanite. For the most light and fire we measure in moissanite, DG-M5 Moissanite. For more sparkle at the same light, T105 Round Brilliant Moissanite or DG-Vitruvio Moissanite.

T73 Round Brilliant Moissanite: questions

Is a round brilliant good for moissanite?

The T73 gives Brilliance 86, Fire 97 and 7% leakage in moissanite. Rounds drawn for moissanite return more light: DG-Anteros 92, DG-M5 98.

T73 or T57 for a moissanite?

Level on light (86 against 85) and fire (97 against 98). The T73 sparkles more in our census and has a girdle band to set.

Does a round moissanite have more fire than a round diamond?

In our census, yes: Fire 97 against 78, from moissanite's higher dispersion.

What does a 6.5 mm round moissanite weigh?

A T73 that wide weighs 0.92 ct in moissanite and 1.01 ct in diamond.

Get the T73 Round Brilliant Cut files

6 formatsMillimetresWatertight

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.

  • STEPExact faceted solid for CAD
  • 3DMRhino, closed mesh on its own layer
  • STLWatertight mesh for printing and casting
  • OBJMesh for modelling and rendering
  • FBXBlender, 3ds Max, Maya, Cinema 4D, Unity, Unreal
  • GLBWeb, AR and quick previews
€9.99 · Personal useBuy the 3D files
GemCad96 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.

  • .ascGemCad design file, 96 index gear
  • .csvTier table: angles, indices and cutting order
  • DiagramPrintable faceting diagram
€9.99 · Personal useBuy the cutting files

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Moissanite: optical properties and the top ten cuts · The T73 Round Brilliant: specifications, model and files

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The T73 Round Brilliant in other gemstones