Asscher Cut Spinel: Pros, Cons and Scores

Spinel has a refractive index of 1.712 to 1.747 and a dispersion of 0.020. Its critical angle, from the low end of that range, is 35.7°, so a round design needs a pavilion of at least 36.1° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 1.730, the midpoint of the published range, and a fire spread of 0.017, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 1.712, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the Asscher Cut in spinel live.

The Asscher Cut has 58 facets and a total depth of 60.4% of its width; its pavilion mains sit at 27.6°. In spinel, the census returns 67 of 100 for brilliance and 58 for fire, against 94 and 47 for the T73, our benchmark, in the same stone; the same Asscher Cut in diamond reads 69 and 80.

Is spinel good in an Asscher? Pros and cons, measured

Pros

Holds its light better in spinel than in diamond 86 vs 79

Cons

Returns less light than the T73 in spinel 67 vs 94
Leaks more light than the T73 in spinel 31 vs 6
Less fire in spinel than in diamond 58 vs 80
Fewer facets, less sparkle 72 vs 80

Compared with the T73 Round Brilliant in spinel and with the Asscher Cut 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.

All eight scores against the T73

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

Global72, the comparison 81, difference −9
Brilliance67, the comparison 94, difference −27
Fire58, the comparison 47, difference +11
Scintillation72, the comparison 80, difference −8
Spread107, the comparison 100, difference +7
Symmetry100, the comparison 100, difference 0
Shape-norm89, the comparison 101, difference −12
Tilt86, the comparison 75, difference +11

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; these are the same census figures as our Cut Performance Index.

What the Asscher Cut gains in spinel

Holds its light better in spinel than in diamond

Tilt 86 against 79 for the Asscher Cut in diamond: 7 points higher

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 Asscher Cut keeps 86 against 79 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.

Asscher cut in spinel tilted 0 degrees: Light Return map, 33% 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; gray is leakage. The share under each frame is that picture's own.

Asscher cut in spinel tilted 10 degrees: Light Return map, 31% 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; gray is leakage. The share under each frame is that picture's own.

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

What the Asscher Cut gives up in spinel

Returns less light than the T73 in spinel

Brilliance 67 against 94 for the T73 Round Brilliant in spinel: 27 points lower

Brilliance is the share of the 3,200 census rays that enter the stone and come back out of the crown towards the viewer. In spinel, whose critical angle is 35.7°, the Asscher Cut returns 67 of 100 and the T73 94. The Asscher Cut's pavilion mains sit at 27.6°, the T73's at 40.8°. The maps below show where each stone's light returns from and where it leaks.

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

T73 round brilliant in spinel face-up Light Return map: red, green and blue show where the light returns from, gray shows where it leaks (Brilliance 94) — 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.

What helps: the DG-M5 reads 100 for brilliance in spinel, the best of the cuts we score there.

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

Leaks more light than the T73 in spinel

Leakage 31 against 6 for the T73 Round Brilliant in spinel: 25 points higher

Leakage is the share of the census rays that enter the stone and leave through the pavilion, or through the crown heading down. The Asscher Cut leaks 31% in spinel against 6% for the T73 in spinel. Grey in the maps below is leaking light; the share under each picture is that picture's own.

What helps: the DG-M5 reads 0% for leakage in spinel, the best of the cuts we score there.

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

Less fire in spinel than in diamond

Fire 58 against 80 for the Asscher Cut in diamond: 22 points lower

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 (0.017 in spinel) and counts a ray as fire when the two directions differ by more than 0.6°. The Asscher Cut reads 58 against 80 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders spinel'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: the Asscher Cut in spinel under the sunny-day lighting.

What helps: the DG-Elongated Hexagon reads 80 for fire in spinel, the best of the cuts we score there.

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

Fewer facets, less sparkle

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

Scintillation follows the number of facets the stone shows: 100 × (1 − e^(−facets / 45)). The Asscher Cut has 58 facets and the T73 73, so 72 against 80. It depends on the geometry alone, so it is the same in every stone.

Asscher Cut · 58 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. Compare the facet counts under the drawings; each drawing shows only the crown. Drawn from each cut's own model.

What helps: the DG-Miliano reads 98 for scintillation in spinel, the best of the cuts we score there.

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

Our verdict on the Asscher Cut in spinel

Pick the Asscher Cut in spinel for this: it holds its light better than in diamond when tilted. The catch: it returns less light than the T73, leaks more light than the T73, shows less fire than in diamond and has fewer facets to sparkle with.

If that catch matters more to you, the DG-M5 reads 100 for brilliance in spinel, 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 Asscher Cut model we traced.

Asscher Cut Spinel: questions

Is the Asscher a good cut for spinel?

In our census the Asscher Cut returns 67 of 100 for brilliance and 58 for fire in spinel, against 94 and 47 for the T73 in the same stone. Against that round and against the same cut in diamond it has 1 pro and 4 cons by our thresholds; the summary above names them.

What pavilion angle does spinel need?

At least 36.1° for a round design: spinel's critical angle is 35.7°, 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 Asscher Cut's pavilion mains sit at 27.6°.

How much does a Asscher weigh in spinel?

At 6.5 mm across, 1.38 ct in spinel, against 1.34 ct for the same cut in diamond (+3%): spinel's specific gravity is 3.62, diamond's 3.52.

Can I see the Asscher in spinel in 3D?

Yes: the 3D Gemstone Simulator renders it live, with spinel's own refractive index and dispersion. Spinel 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.

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Asscher Cut 3D files

The Asscher Cut as exact geometry: 58 planar facets, real-world scale, ready for CAD, rendering, printing and casting.

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Asscher Cut cutting files

The Asscher Cut as a faceting design: 58 facets, 96 index, 4-fold symmetry, ready for the machine.

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More gemstones and cuts

Spinel: optical properties and the top ten cuts · The Asscher Cut: specifications, model and files

Asscher Cut Spinel: holds its light better in spinel than in diamond