Brilliance 93 · Fire 47 · Scintillation 98 · in our census, where the T73 scores 94 · 47 · 80 in spinel
How the DG-Vitruvio handles light in spinel, measured: brilliance 93, fire 47 and 7% leakage, set against the T73 in the same stone and against the same cut in diamond.
Light Return map of the DG-Vitruvio in spinel, face-up, from our own tracer at refractive index 1.712. Red, green and blue return light to the eye; gray leaks.
DG-Vitruvio Spinel
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 DG-Vitruvio in spinel live.
The DG-Vitruvio has 153 facets and a total depth of 61.9% of its width; its pavilion mains sit at 40.8°. In spinel, the census returns 93 of 100 for brilliance and 47 for fire, against 94 and 47 for the T73, our benchmark, in the same stone; the same DG-Vitruvio in diamond reads 93 and 79.
Is spinel good in a DG-Vitruvio? Pros and cons, measured
Compared with the T73 Round Brilliant in spinel and with the DG-Vitruvio 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 DG-Vitruvio 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 2, level on 4, behind on 2.
Global82, the comparison 81, difference +1
Brilliance93, the comparison 94, difference −1
Fire47, the comparison 47, difference 0
Scintillation98, the comparison 80, difference +18
Spread100, the comparison 100, difference 0
Symmetry100, the comparison 100, difference 0
Shape-norm100, the comparison 101, difference −1
Tilt75, the comparison 75, difference 0
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 DG-Vitruvio gains in spinel
More facets, more sparkle
Scintillation 98 against 80 for the T73 Round Brilliant in spinel: 18 points higher
Scintillation follows the number of facets the stone shows: 100 × (1 − e^(−facets / 45)). The DG-Vitruvio has 153 facets and the T73 73, so 98 against 80. It depends on the geometry alone, so it is the same in every stone.
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.
Fire 47 against 79 for the DG-Vitruvio in diamond: 32 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 DG-Vitruvio reads 47 against 79 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 DG-Vitruvio 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.
Tilt 75 against 93 for the DG-Vitruvio in diamond: 18 points lower
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 DG-Vitruvio keeps 75 against 93 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.
DG-Vitruvio in spinel · Tilt 75
0° · 0% leak
10° · 16% leak
20° · 30% leak
30° · 32% leak
DG-Vitruvio in diamond · Tilt 93
0° · 4% leak
10° · 2% leak
20° · 9% leak
30° · 15% leak
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.
What helps:the DG-Miliano reads 82 for tilt in spinel, the best of the cuts we score there.
Leakage 7 against 2 for the DG-Vitruvio in diamond: 5 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 DG-Vitruvio leaks 7% in spinel against 2% for the same cut in diamond. Grey in the maps below is leaking light; the share under each picture is that picture's own.
DG-Vitruvio in spinel · Leakage 7
0° · 0% leak
10° · 16% leak
20° · 30% leak
30° · 32% leak
DG-Vitruvio in diamond · Leakage 2
0° · 4% leak
10° · 2% leak
20° · 9% leak
30° · 15% leak
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.
What helps:the DG-M5 reads 0% for leakage in spinel, the best of the cuts we score there.
Pick the DG-Vitruvio in spinel for this: it has more facets to sparkle with. The catch: it shows less fire than in diamond, loses more light when tilted than in diamond and leaks more than in diamond.
If that catch matters more to you, the DG-Elongated Hexagon reads 80 for fire 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 DG-Vitruvio model we traced.
DG-Vitruvio Spinel: questions
Is the DG-Vitruvio a good cut for spinel?
In our census the DG-Vitruvio returns 93 of 100 for brilliance and 47 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 3 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 DG-Vitruvio's pavilion mains sit at 40.8°.
How much does a DG-Vitruvio weigh in spinel?
At 6.5 mm across, 1.05 ct in spinel, against 1.02 ct for the same cut in diamond (+3%): spinel's specific gravity is 3.62, diamond's 3.52.
Can I see the DG-Vitruvio 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.
Get the DG-Vitruvio Cut files
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DG-Vitruvio Cut 3D files
The DG-Vitruvio Cut as exact geometry: 265 planar facets, real-world scale, ready for CAD,
rendering, printing and casting.
