Old Single Cut Moissanite: Pros, Cons & Fire

Moissanite splits light into colour more than twice as strongly as diamond (dispersion 0.104 against 0.044). Put that in the Old Single's large facets and you get one of the highest fire scores we measure: only DG-M5 scores higher in moissanite.

The same few facets cost sparkle and some light. This page sets the stone against the same cut in diamond and against the T73 in moissanite.

Is moissanite good in an Old Single cut? Pros and cons

Pros

Far more fire than the same cut in diamond 99 vs 84
Lighter for its size 0.96 vs 1.05 ct
Leaks less than in diamond 12 vs 19

Cons

Far fewer flashes than a modern round 44 vs 80
Less light than the T73 in moissanite 77 vs 86
Loses more light when tilted 89 vs 94
A little smaller for its weight 97 vs 100

Compared with the T73 Round Brilliant in moissanite and with the Old Single 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 Old Single 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 1, behind on 6.

Global83, the comparison 91, difference −8
Brilliance77, the comparison 86, difference −9
Fire99, the comparison 97, difference +2
Scintillation44, the comparison 80, difference −36
Spread97, the comparison 100, difference −3
Symmetry100, the comparison 100, difference 0
Shape-norm82, the comparison 93, difference −11
Tilt89, the comparison 94, difference −5

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 Old Single cut

Far more fire than the same cut in diamond

Fire 99 against 84 for the Old Single Cut in diamond: 15 points higher

Most of this is moissanite itself: its dispersion is more than twice diamond's. Compare the coloured flashes in the two renders: larger and brighter in the moissanite.

Old single cut in moissanite face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 99) — 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.

Old single cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 84) — 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 for its size

0.96 ct at 6.5 mm, against 1.05 ct for the same cut in diamond (−9%)

Moissanite's specific gravity is 3.22 against diamond's 3.52, so the same size weighs less.

A Old Single 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 Old Single Cut page

Leaks less than in diamond

Leakage 12 against 19 for the Old Single Cut in diamond: 7 points lower

Moissanite's higher refractive index keeps more light inside: 12% leaks in our census, against 19% for the same cut in diamond.

Old single cut in moissanite tilted 0 degrees: Light Return map, 16% of the face leaking — 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.

Old single cut in moissanite tilted 10 degrees: Light Return map, 16% of the face leaking — 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: Tilt it yourself in the simulator's light map

The catch with an Old Single moissanite

Far fewer flashes than a modern round

Scintillation 44 against 80 for the T73 Round Brilliant in moissanite: 36 points lower

26 facets against the T73's 73: the sparkle is slow and bold, not fine.

Old Single Cut · 26 facets · Scintillation 44

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: This is the facet plan. The Old European Cut Moissanite keeps an antique round with 81 for scintillation.

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

Less light than the T73 in moissanite

Brilliance 77 against 86 for the T73 Round Brilliant in moissanite: 9 points lower

The T73 returns more light in moissanite, though its angles were worked out for diamond.

Old single cut in moissanite face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 77) — 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: For light in moissanite, DG-Anteros (92) is the round we designed for it.

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

Loses more light when tilted

Tilt 89 against 94 for the T73 Round Brilliant in moissanite: 5 points lower

Tipped by 20°, it keeps less of its face-up light than the T73: 89 against 94. The strip shows the grey growing as it tips.

What helps: Set it face-up, in a ring rather than a pendant that swings.

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

A little smaller for its weight

Spread 97 against 100 for the T73 Round Brilliant in moissanite: 3 points lower

At 67.5% deep, a stone of the same carat weight is slightly narrower than a T73.

Old Single Cut · 6.58 mm at 1.00 ct · Spread 97

T73 Round Brilliant · 6.68 mm at 1.00 ct · Spread 100

Both stones weigh 1.00 ct in moissanite and are drawn to the same scale, from each cut's own model. Spread is face-up size per carat: a deeper stone carries more weight below the girdle and looks smaller for its weight.

What helps: Moissanite is usually chosen by size: a 6.5 mm Old Single weighs 0.96 ct.

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

Who an Old Single moissanite suits

For colour above all, this is one of the strongest choices we measure: an antique outline with fire close to the top of our scale. It suits accent stones and anyone who wants a stone that flashes colour across a room.

If you want brightness and fine sparkle, DG-Anteros Moissanite returns more light, and the Old European Cut Moissanite keeps an antique look with many more facets.

Old Single Cut Moissanite: questions

Does Old Single cut moissanite have a lot of fire?

Yes. It scores 99 for fire, against 84 for the same cut in diamond and 97 for the T73 in moissanite.

Is Old Single cut moissanite too sparkly?

It is fiery rather than sparkly: with 26 facets its scintillation is 44, against 80 for a modern round.

Will an Old Single moissanite look doubled?

Moissanite is doubly refractive, but our renders trace a single index, so they cannot show doubling. Cutters orient the table across the optic axis to hide it.

Get the Old Single Cut files

6 formatsMillimetresWatertight

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.

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

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.

.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 Old Single Cut: specifications, model and files

Old Single Cut Moissanite: almost all the fire our census can measure