T57 Round Brilliant Moissanite: near-top fire from the plainest round brilliant plan

Brilliance 85 · Fire 98 · Scintillation 72 · in our census, where the T73 scores 86 · 97 · 80 in moissanite

The knife-edge round with nothing added: in moissanite its fire sits near the top of our scale, and its sparkle trails the T73's.

See it in the simulatorGet the files
The T57 Round Brilliant in moissanite, rendered at an angle in our 3D Gemstone Simulator under studio light
Rendered in our 3D Gemstone Simulator from the T57 Round Brilliant model, 1.00 ct, studio light.

T57 Round Brilliant Moissanite

The T57 is the round brilliant with a knife-edge girdle, cut to the proportions Marcel Tolkowsky published in 1919. Table, eight stars, eight bezels, sixteen upper halves, eight pavilion mains and sixteen lower halves: 57 facets, 59.2% deep, with a 40.75° pavilion.

We keep it for teaching, comparison and period work. In moissanite it is level with the T73 on light and fire; the girdle band the T73 adds is what lifts the T73's sparkle.

Its fire, 98, ties for third among the cuts we sell in moissanite, level with DG-Bowtie and behind only DG-M5 and the Old Single.

T57 cut moissanite: worth it? Pros and cons

Pros

Cons

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

At a glance: the T57 Round Brilliant in moissanite (white) against the T73 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: T57 Round Brilliant in moissanite, against the T73 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 T73 Round Brilliant in moissanite: ahead on 2, level on 1, behind on 5.

  • Global90, the comparison 91, difference −1
  • Brilliance85, the comparison 86, difference −1
  • Fire98, the comparison 97, difference +1
  • Scintillation72, the comparison 80, difference −8
  • Spread101, the comparison 100, difference +1
  • Symmetry100, the comparison 100, difference 0
  • Shape-norm92, the comparison 93, difference −1
  • Tilt93, the comparison 94, 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 T57

Far more fire than a diamond T57

Fire 98 against 79 for the T57 Round Brilliant in diamond: 19 points higher

Through the same 57 facets, diamond reaches 79 and moissanite 98. The gap belongs to the material, whose dispersion is more than double diamond's, not to the plan.

T57 round brilliant in moissanite face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 98)

T57 Round Brilliant in moissanite · Fire 98

T57 round brilliant in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 79)

T57 Round Brilliant in diamond · Fire 79

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 in diamond

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

Specific gravity 3.22 against 3.52: the moissanite T57 carries less weight for every millimetre of width.

Moissanite0.84 ctDiamond0.92 ct
A T57 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 T57 Round Brilliant page

The catch with a T57 moissanite

Less sparkle than the T73

Scintillation 72 against 80 for the T73 Round Brilliant in moissanite: 8 points lower

Our scintillation score counts facets, and the T57 has 57 against the T73's 73. The difference is the T73's sixteen girdle facets; the crown and pavilion are the same.

T57 Round Brilliant · 57 facets · Scintillation 72

T73 Round Brilliant · 73 facets · Scintillation 80

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.

What helps: The plan sets this. Adding the girdle band gives the T73 Round Brilliant Moissanite (80); dividing the halves further gives the T105 Round Brilliant Moissanite (90), still with a knife edge.

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

Less light than in diamond

Brilliance 85 against 92 for the T57 Round Brilliant in diamond: 7 points lower

The diamond T57 returns 92; in moissanite the same proportions return 85, about the T73's level in this stone.

T57 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 85)

T57 Round Brilliant in moissanite · Brilliance 85

T57 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 92)

T57 Round Brilliant in diamond · Brilliance 92

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: For more light in a round moissanite, DG-M5 Moissanite at 98 or DG-Anteros Moissanite at 92.

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

More leakage than in diamond

Leakage 8 against 2 for the T57 Round Brilliant in diamond: 6 points higher

Of the light in our census, 8% goes out through the pavilion, where the diamond T57 loses 2%.

T57 Round Brilliant in moissanite · Leakage 8

T57 round brilliant in moissanite tilted 0 degrees: Light Return map, 9% of the face leaking0° · 9% leak
T57 round brilliant in moissanite tilted 10 degrees: Light Return map, 7% of the face leaking10° · 7% leak
T57 round brilliant in moissanite tilted 20 degrees: Light Return map, 12% of the face leaking20° · 12% leak
T57 round brilliant in moissanite tilted 30 degrees: Light Return map, 16% of the face leaking30° · 16% leak

T57 Round Brilliant in diamond · Leakage 2

T57 round brilliant in diamond tilted 0 degrees: Light Return map, 4% of the face leaking0° · 4% leak
T57 round brilliant in diamond tilted 10 degrees: Light Return map, 2% of the face leaking10° · 2% leak
T57 round brilliant in diamond tilted 20 degrees: Light Return map, 10% of the face leaking20° · 10% leak
T57 round brilliant in diamond tilted 30 degrees: Light Return map, 16% of the face leaking30° · 16% 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: The share holds at any size, and at 40.75° the pavilion is already past the 39.5° guide minimum; steepening is not the remedy. DG-M5 leaks 1%, DG-Anteros 3%.

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

Who a T57 moissanite suits

The T57 suits period work, teaching and side-by-side comparison, and a moissanite where fire matters more than sparkle. Its knife-edge girdle needs protecting in a setting.

For a round to set every day, the T73 Round Brilliant Moissanite adds a girdle a setter can seat. For more light, DG-M5 Moissanite.

T57 Round Brilliant Moissanite: questions

Is a T57 round good for moissanite?

For fire, yes: 98, near the top of our scale. Its scintillation, 72, trails the T73's 80.

What is the difference between the T57 and the T73?

Sixteen girdle facets. In moissanite that moves scintillation from 72 to 80; light and fire stay within a point.

Does a T57 moissanite leak light?

8% in our census, against 7% for the T73 and 2% for a diamond T57.

What does a 6.5 mm T57 moissanite weigh?

0.84 ct in moissanite; 0.92 ct for a diamond of the same width.

Get the T57 Round Brilliant Cut files

6 formatsMillimetresWatertight

T57 Round Brilliant Cut 3D files

The T57 Round Brilliant Cut as exact geometry: 57 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

T57 Round Brilliant Cut cutting files

The T57 Round Brilliant Cut as a faceting design: 57 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

Questions before you buy? Email us.

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Moissanite: optical properties and the top ten cuts · The T57 Round Brilliant: specifications, model and files

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The T57 Round Brilliant in other gemstones