Brilliance 85 · Fire 41 · Scintillation 98 · in our census, where the T73 scores 92 · 47 · 80 in tanzanite
How the DG-Miliano handles light in tanzanite, measured: brilliance 85, fire 41 and 15% leakage, set against the T73 in the same stone and against the same cut in diamond.
Light Return map of the DG-Miliano in tanzanite, face-up, from our own tracer at refractive index 1.685. Red, green and blue return light to the eye; gray leaks.
DG-Miliano Tanzanite
Tanzanite has a refractive index of 1.685 to 1.707 and a dispersion of 0.019. Its critical angle, from the low end of that range, is 36.4°, so a round design needs a pavilion of at least 36.4° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 1.696, the midpoint of the published range, and a fire spread of 0.016, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 1.685, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the DG-Miliano in tanzanite live.
The DG-Miliano has 177 facets and a total depth of 60.3% of its width; its pavilion mains sit at 38.3°. In tanzanite, the census returns 85 of 100 for brilliance and 41 for fire, against 92 and 47 for the T73, our benchmark, in the same stone; the same DG-Miliano in diamond reads 95 and 82.
Is tanzanite good in a DG-Miliano? Pros and cons, measured
Compared with the T73 Round Brilliant in tanzanite and with the DG-Miliano 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-Miliano in tanzanite (white) against the T73 Round Brilliant in tanzanite (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 tanzanite: ahead on 3, level on 1, behind on 4.
Global79, the comparison 80, difference −1
Brilliance85, the comparison 92, difference −7
Fire41, the comparison 47, difference −6
Scintillation98, the comparison 80, difference +18
Spread101, the comparison 100, difference +1
Symmetry100, the comparison 100, difference 0
Shape-norm91, the comparison 99, difference −8
Tilt84, the comparison 73, 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 DG-Miliano gains in tanzanite
More facets, more sparkle
Scintillation 98 against 80 for the T73 Round Brilliant in tanzanite: 18 points higher
Scintillation follows the number of facets the stone shows: 100 × (1 − e^(−facets / 45)). The DG-Miliano has 177 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.
0.98 ct at 6.5 mm, against 1.03 ct for the same cut in diamond (−5%)
Weight follows specific gravity: 3.35 for tanzanite against 3.52 for diamond, so the same model at the same size weighs 0.98 ct here and 1.03 ct in diamond, 6.5 mm across. Nothing about the light changes with it.
A DG-Miliano 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.
Fire 41 against 82 for the DG-Miliano in diamond: 41 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 (0.016 in tanzanite) and counts a ray as fire when the two directions differ by more than 0.6°. The DG-Miliano reads 41 against 82 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders tanzanite'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-Miliano in tanzanite under the sunny-day lighting.
What helps:the DG-Elongated Hexagon reads 79 for fire in tanzanite, the best of the cuts we score there.
Leakage 15 against 3 for the DG-Miliano in diamond: 12 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-Miliano leaks 15% in tanzanite against 3% 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-Miliano in tanzanite · Leakage 15
0° · 13% leak
10° · 18% leak
20° · 28% leak
30° · 32% leak
DG-Miliano in diamond · Leakage 3
0° · 1% leak
10° · 4% leak
20° · 7% leak
30° · 16% 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 tanzanite, the best of the cuts we score there.
Brilliance 85 against 95 for the DG-Miliano in diamond: 10 points lower
The same cut in diamond returns 95. Tanzanite bends light less than diamond: its critical angle is 36.4°, diamond's 24.4°, so a pavilion facet has to be steeper before light reflects off it rather than passing out. The DG-Miliano's pavilion returns less of tanzanite's light than of diamond's, as the two maps show.
DG-Miliano in tanzanite · Brilliance 85
DG-Miliano in diamond · Brilliance 95
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 tanzanite, the best of the cuts we score there.
Tilt 84 against 90 for the DG-Miliano in diamond: 6 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-Miliano keeps 84 against 90 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-Miliano in tanzanite · Tilt 84
0° · 13% leak
10° · 18% leak
20° · 28% leak
30° · 32% leak
DG-Miliano in diamond · Tilt 90
0° · 1% leak
10° · 4% leak
20° · 7% leak
30° · 16% 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.
Pick the DG-Miliano in tanzanite for this: it has more facets to sparkle with and weighs less than in diamond. The catch: it shows less fire than in diamond, leaks more than in diamond, returns less light than in diamond and loses more light when tilted than in diamond.
If that catch matters more to you, the DG-Elongated Hexagon reads 79 for fire in tanzanite, 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-Miliano model we traced.
DG-Miliano Tanzanite: questions
Is the DG-Miliano a good cut for tanzanite?
In our census the DG-Miliano returns 85 of 100 for brilliance and 41 for fire in tanzanite, against 92 and 47 for the T73 in the same stone. Against that round and against the same cut in diamond it has 2 pros and 4 cons by our thresholds; the summary above names them.
What pavilion angle does tanzanite need?
At least 36.4° for a round design: tanzanite's critical angle is 36.4°, 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-Miliano's pavilion mains sit at 38.3°.
How much does a DG-Miliano weigh in tanzanite?
At 6.5 mm across, 0.98 ct in tanzanite, against 1.03 ct for the same cut in diamond (-5%): tanzanite's specific gravity is 3.35, diamond's 3.52.
Can I see the DG-Miliano in tanzanite in 3D?
Yes: the 3D Gemstone Simulator renders it live, with tanzanite's own refractive index and dispersion. Tanzanite 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-Miliano Cut files
6 formatsMillimetersWatertight
DG-Miliano Cut 3D files
The DG-Miliano Cut as exact geometry: 177 planar facets, real-world scale, ready for CAD,
rendering, printing and casting.
