Octagon Cut Moissanite: Pros, Cons & Tilt

Our octagon carries the hexagon's tier profile on eight sides: a stepped crown over a three-tier pavilion, with a 60.0% table, a 39.8° crown and a 29.3° pavilion, 49 facets in all and a total depth of 61.0%.

In moissanite it has three pros, all against the same cut in diamond: fire, weight and tilt. Against the T73 it loses on light, sparkle and leakage, and the leak is large.

Its stepped facets are broad, and moissanite is doubly refractive; our renders trace one index, so any doubling lies outside what we can show.

Octagon cut moissanite: should you choose it? Pros and cons

Pros

More fire than a diamond octagon 94 vs 76
Lighter than in diamond 1.13 vs 1.23 ct
Keeps its light when tipped 100 vs 97

Compared with the T73 Round Brilliant in moissanite and with the Octagon Cut 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 Octagon Cut 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.

Against the T73 Round Brilliant in moissanite: ahead on 1, level on 2, behind on 5.

Global82, the comparison 91, difference −9
Brilliance67, the comparison 86, difference −19
Fire94, the comparison 97, difference −3
Scintillation66, the comparison 80, difference −14
Spread100, the comparison 100, difference 0
Symmetry100, the comparison 100, difference 0
Shape-norm88, the comparison 93, difference −5
Tilt100, the comparison 94, difference +6

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 an octagon cut

More fire than a diamond octagon

Fire 94 against 76 for the Octagon Cut in diamond: 18 points higher

76 in diamond, 94 in moissanite, through identical facets: the difference is the material's dispersion, 0.104 against 0.044.

Octagon cut in moissanite face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 94) — 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.

Octagon cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 76) — 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

1.13 ct at 6.5 mm, against 1.23 ct for the same cut in diamond (−9%)

In diamond a 6.5 mm octagon passes a carat; moissanite, less dense, brings the same stone down to 1.13 ct.

A Octagon Cut 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 Octagon Cut page

Keeps its light when tipped

Tilt 100 against 97 for the Octagon Cut in diamond: 3 points higher

Tilt reads 100, against 97 for the diamond octagon. Its brilliance is within a few points of the diamond's, so the gain counts, though both start from much less light than a round.

Octagon cut in moissanite tilted 0 degrees: Light Return map, 20% of the face leaking — 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; grey is light leaving through the pavilion. The share under each frame is that picture's own.

Octagon cut in moissanite tilted 10 degrees: Light Return map, 19% of the face leaking — 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; grey is light leaving through the pavilion. The share under each frame is that picture's own.

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

The catch with an octagon moissanite

Much less light than a round

Brilliance 67 against 86 for the T73 Round Brilliant in moissanite: 19 points lower

67 against 86 for the T73. Among eight-sided outlines in moissanite, DG-Octagonal Kite returns 71.

Octagon cut in moissanite face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 67) — 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.

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) — 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: The Square Cut Moissanite returns 82 on a four-sided outline; for the most light, DG-M5 Moissanite.

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

Fewer flashes than a round

Scintillation 66 against 80 for the T73 Round Brilliant in moissanite: 14 points lower

With 49 facets against 73, the octagon's scintillation is 66: broad steps flash less often.

Octagon Cut · 49 facets · Scintillation 66

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 step plan sets this. For more flashes, the Cushion Cut Moissanite scores 85.

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

A fifth of the light leaks

Leakage 20 against 7 for the T73 Round Brilliant in moissanite: 13 points higher

A fifth of the light in our census, 20%, is lost out of the octagon's back, nearly three times the T73's 7%. Its 29.3° pavilion figure is far below the 39.5° guide minimum for rounds; we have not measured a steeper octagon, so we make no promise.

What helps: Among cornered outlines, the Square Cut Moissanite leaks 11% and DG-Octagonal Kite Moissanite 14%.

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

Who an octagon moissanite suits

The octagon suits a crisp geometric design in which the stone will move, and colour is wanted. It holds what light it has at every angle.

If brightness matters, the Square Cut Moissanite returns more for a cornered outline; for an eight-sided stone with more light and less leakage, DG-Octagonal Kite Moissanite.

Octagon Cut Moissanite: questions

Is octagon cut moissanite bright?

Not by round standards: Brilliance 67 against 86, with 20% leakage. It holds that light well when tipped, Tilt 100.

Octagon or Asscher cut moissanite?

The octagon returns a little more light (67 against 64) and holds it far better when tipped (100 against 77); the Asscher leaks less (12% against 20%).

Does octagon cut moissanite have fire?

Yes: 94, against 76 for a diamond octagon.

What does a 6.5 mm octagon moissanite weigh?

1.13 ct in moissanite, 1.23 ct in diamond.

Get the Octagon Cut files

6 formatsMillimetresWatertight

Octagon Cut 3D files

The Octagon Cut as exact geometry: 49 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

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.

.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.

More gemstones and cuts

Moissanite: optical properties and the top ten cuts · The Octagon Cut: specifications, model and files

Octagon Cut Moissanite: strong fire, and light that holds when tipped