Brilliance 85 · Fire 36 · Scintillation 98 · in our census, where the T73 scores 86 · 35 · 80 in topaz
How the DG-Vitruvio handles light in topaz, measured: brilliance 85, fire 36 and 15% leakage, set against the T73 in the same stone and against the same cut in diamond.
Light Return map of the DG-Vitruvio in topaz, face-up, from our own tracer at refractive index 1.606. Red, green and blue return light to the eye; gray leaks.
DG-Vitruvio Topaz
Topaz has a refractive index of 1.606 to 1.644 and a dispersion of 0.014. Its critical angle, from the low end of that range, is 38.5°, so a round design needs a pavilion of at least 38.5° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 1.625, the midpoint of the published range, and a fire spread of 0.012, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 1.606, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the DG-Vitruvio in topaz 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 topaz, the census returns 85 of 100 for brilliance and 36 for fire, against 86 and 35 for the T73, our benchmark, in the same stone; the same DG-Vitruvio in diamond reads 93 and 79.
Is topaz good in a DG-Vitruvio? Pros and cons, measured
Compared with the T73 Round Brilliant in topaz 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 topaz (white) against the T73 Round Brilliant in topaz (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 topaz: ahead on 4, level on 2, behind on 2.
Global76, the comparison 75, difference +1
Brilliance85, the comparison 86, difference −1
Fire36, the comparison 35, difference +1
Scintillation98, the comparison 80, difference +18
Spread100, the comparison 100, difference 0
Symmetry100, the comparison 100, difference 0
Shape-norm91, the comparison 92, difference −1
Tilt75, the comparison 74, difference +1
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 topaz
More facets, more sparkle
Scintillation 98 against 80 for the T73 Round Brilliant in topaz: 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 36 against 79 for the DG-Vitruvio in diamond: 43 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 (0.012 in topaz) and counts a ray as fire when the two directions differ by more than 0.6°. The DG-Vitruvio reads 36 against 79 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders topaz'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 topaz under the sunny-day lighting.
What helps:the Oval Cut reads 68 for fire in topaz, 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 topaz · Tilt 75
0° · 12% leak
10° · 28% leak
20° · 32% leak
30° · 37% 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 T105 Round Brilliant reads 78 for tilt in topaz, the best of the cuts we score there.
Leakage 15 against 2 for the DG-Vitruvio in diamond: 13 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 15% in topaz 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 topaz · Leakage 15
0° · 12% leak
10° · 28% leak
20° · 32% leak
30° · 37% 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 4% for leakage in topaz, the best of the cuts we score there.
Brilliance 85 against 93 for the DG-Vitruvio in diamond: 8 points lower
The same cut in diamond returns 93. Topaz bends light less than diamond: its critical angle is 38.5°, diamond's 24.4°, so a pavilion facet has to be steeper before light reflects off it rather than passing out. The DG-Vitruvio's pavilion returns less of topaz's light than of diamond's, as the two maps show.
DG-Vitruvio in topaz · Brilliance 85
DG-Vitruvio in diamond · Brilliance 93
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 96 for brilliance in topaz, the best of the cuts we score there.
Pick the DG-Vitruvio in topaz 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, leaks more than in diamond and returns less light than in diamond.
If that catch matters more to you, the Oval Cut reads 68 for fire in topaz, 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 Topaz: questions
Is the DG-Vitruvio a good cut for topaz?
In our census the DG-Vitruvio returns 85 of 100 for brilliance and 36 for fire in topaz, against 86 and 35 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 topaz need?
At least 38.5° for a round design: topaz's critical angle is 38.5°, 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 topaz?
At 6.5 mm across, 1.02 ct in topaz, against 1.02 ct for the same cut in diamond, the same weight to the per cent: topaz's specific gravity is 3.535, diamond's 3.52.
Can I see the DG-Vitruvio in topaz in 3D?
Yes: the 3D Gemstone Simulator renders it live, with topaz's own refractive index and dispersion. Topaz 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.
