Old Single Cut Synthetic rutile: more fire in synthetic rutile than in diamond
Brilliance 77 · Fire 97 · Scintillation 44 · in our census, where the T73 scores 81 · 94 · 80 in synthetic rutile
How the Old Single Cut handles light in synthetic rutile, measured: brilliance 77, fire 97 and 11% leakage, set against the T73 in the same stone and against the same cut in diamond.
Light Return map of the Old Single Cut in synthetic rutile, face-up, from our own tracer at refractive index 2.616. Red, green and blue return light to the eye; gray leaks.
Old Single Cut Synthetic rutile
Synthetic rutile has a refractive index of 2.616 to 2.903 and a dispersion of 0.330. Its critical angle, from the low end of that range, is 22.5°, so a round design needs a pavilion of at least 39.4° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 2.760, the midpoint of the published range, and a fire spread of 0.284, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 2.616, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the Old Single Cut in synthetic rutile live. Synthetic rutile is strongly doubly refractive (birefringence 0.287): its two rays have critical angles of 22.5° and 20.1°. Our census traces one index, so every figure for it is a rough approximation.
The Old Single Cut has 26 facets, a table of 57.5% of its width and a total depth of 67.5% of its width; its pavilion mains sit at 48.5°. In synthetic rutile, the census returns 77 of 100 for brilliance and 97 for fire, against 81 and 94 for the T73, our benchmark, in the same stone; the same Old Single Cut in diamond reads 72 and 84.
Is synthetic rutile good in an Old Single? Pros and cons, measured
Compared with the T73 Round Brilliant in synthetic rutile and with the Old Single 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 Old Single Cut in synthetic rutile (white) against the T73 Round Brilliant in synthetic rutile (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 synthetic rutile: ahead on 1, level on 1, behind on 6.
Global83, the comparison 88, difference −5
Brilliance77, the comparison 81, difference −4
Fire97, the comparison 94, difference +3
Scintillation44, the comparison 80, difference −36
Spread97, the comparison 100, difference −3
Symmetry100, the comparison 100, difference 0
Shape-norm83, the comparison 87, difference −4
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. 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 Old Single Cut gains in synthetic rutile
More fire in synthetic rutile than in diamond
Fire 97 against 84 for the Old Single Cut in diamond: 13 points higher
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 (0.284 in synthetic rutile) and counts a ray as fire when the two directions differ by more than 0.6°. The Old Single Cut reads 97 against 84 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders synthetic rutile'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 Old Single Cut in synthetic rutile under the sunny-day lighting.
Leakage 11 against 19 for the Old Single Cut in diamond: 8 points lower
Leakage is the share of the census rays that enter the stone and leave through the pavilion, or through the crown heading down. The Old Single Cut leaks 11% in synthetic rutile against 19% for the same cut in diamond. Grey in the maps below is leaking light; the share under each picture is that picture's own.
Old Single Cut in synthetic rutile · Leakage 11
0° · 12% leak
10° · 15% leak
20° · 26% leak
30° · 31% leak
Old Single Cut in diamond · Leakage 19
0° · 23% leak
10° · 19% leak
20° · 27% leak
30° · 35% 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.
Brilliance 77 against 72 for the Old Single Cut in diamond: 5 points higher
The same cut in diamond returns 72. Synthetic rutile bends light less than diamond: its critical angle is 22.5°, diamond's 24.4°, so a pavilion facet has to be steeper before light reflects off it rather than passing out. The Old Single Cut's pavilion returns more of synthetic rutile's light than of diamond's, as the two maps show.
Old Single Cut in synthetic rutile · Brilliance 77
Old Single Cut in diamond · Brilliance 72
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 the Old Single Cut gives up in synthetic rutile
Fewer facets, less sparkle
Scintillation 44 against 80 for the T73 Round Brilliant in synthetic rutile: 36 points lower
Scintillation follows the number of facets the stone shows: 100 × (1 − e^(−facets / 45)). The Old Single Cut has 26 facets and the T73 73, so 44 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.
What helps:the DG-Miliano reads 98 for scintillation in synthetic rutile, the best of the cuts we score there.
1.27 ct at 6.5 mm, against 1.05 ct for the same cut in diamond (+21%)
Weight follows specific gravity: 4.26 for synthetic rutile against 3.52 for diamond, so the same model at the same size weighs 1.27 ct here and 1.05 ct in diamond, 6.5 mm across. Nothing about the light changes with it.
A Old Single Cut 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.
Face-up size 90 against 100 for the T73 Round Brilliant in synthetic rutile (T73 = 100): 10% less face-up area for the same weight
Face-up size is the outline's area per carat, measured from each model (T73 = 100): 90 for the Old Single Cut against 100 for the T73. The same volume spread over a longer or shallower outline shows more face for the weight; it is the same in every stone, because specific gravity scales every cut alike.
Old Single Cut · 5.99 mm at 1.00 ct · Face-up size 90
T73 Round Brilliant · 6.08 mm at 1.00 ct · Face-up size 100
Both stones weigh 1.00 ct in synthetic rutile and are drawn to the same scale in millimeters, from each cut's own model. Face-up size is the outline's area per carat, with the T73 at 100: a deeper stone, or a rounder outline, spreads less area for its weight.
What helps:the Marquise Cut reads 121 for face-up size in synthetic rutile, the best of the cuts we score there.
Tilt 89 against 94 for the T73 Round Brilliant in synthetic rutile: 5 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 Old Single Cut keeps 89 against 94 for the T73. The tilt strips below show the maps at 0°, 10°, 20° and 30°, with each picture's own leak share under it.
Old Single Cut in synthetic rutile · Tilt 89
0° · 12% leak
10° · 15% leak
20° · 26% leak
30° · 31% leak
T73 Round Brilliant in synthetic rutile · Tilt 94
0° · 10% leak
10° · 6% leak
20° · 10% 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 Old European Cut reads 100 for tilt in synthetic rutile, the best of the cuts we score there.
Our verdict on the Old Single Cut in synthetic rutile
Pick the Old Single Cut in synthetic rutile for this: it shows more fire than in diamond, leaks less than in diamond and returns more light than in diamond. The catch: it has fewer facets to sparkle with, weighs more than in diamond, faces up smaller for its weight and loses more of its light when tilted.
If that catch matters more to you, the DG-Miliano reads 98 for scintillation in synthetic rutile, 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 Old Single Cut model we traced.
Old Single Cut Synthetic rutile: questions
Is the Old Single a good cut for synthetic rutile?
In our census the Old Single Cut returns 77 of 100 for brilliance and 97 for fire in synthetic rutile, against 81 and 94 for the T73 in the same stone. Against that round and against the same cut in diamond it has 3 pros and 4 cons by our thresholds; the summary above names them.
What pavilion angle does synthetic rutile need?
At least 39.4° for a round design: synthetic rutile's critical angle is 22.5°, 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 Old Single Cut's pavilion mains sit at 48.5°.
How much does a Old Single weigh in synthetic rutile?
At 6.5 mm across, 1.27 ct in synthetic rutile, against 1.05 ct for the same cut in diamond (+21%): synthetic rutile's specific gravity is 4.26, diamond's 3.52.
Can I see the Old Single in synthetic rutile in 3D?
Yes: the 3D Gemstone Simulator renders it live, with synthetic rutile's own refractive index and dispersion. Synthetic rutile 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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Old Single Cut 3D files
The Old Single Cut as exact geometry: 26 planar facets, real-world scale, ready for CAD,
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