Emerald Square Cut YAG: holds its light better in YAG than in diamond
Brilliance 68 · Fire 62 · Scintillation 72 · in our census, where the T73 scores 96 · 54 · 80 in YAG
How the Emerald Square Cut handles light in YAG, measured: brilliance 68, fire 62 and 23% leakage, set against the T73 in the same stone and against the same cut in diamond.
Light Return map of the Emerald Square Cut in YAG, face-up, from our own tracer at refractive index 1.833. Red, green and blue return light to the eye; gray leaks.
Emerald Square Cut YAG
YAG has a refractive index of 1.833 and a dispersion of 0.028. Its critical angle, from the low end of that range, is 33.1°, so a round design needs a pavilion of at least 36.7° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 1.833, the midpoint of the published range, and a fire spread of 0.024, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 1.833, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the Emerald Square Cut in YAG live.
The Emerald Square Cut has 49 facets and a total depth of 61.0% of its width; its pavilion mains sit at 28.3°. In YAG, the census returns 68 of 100 for brilliance and 62 for fire, against 96 and 54 for the T73, our benchmark, in the same stone; the same Emerald Square Cut in diamond reads 64 and 84.
Is YAG good in an Emerald Square? Pros and cons, measured
Compared with the T73 Round Brilliant in YAG and with the Emerald Square 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 Emerald Square Cut in YAG (white) against the T73 Round Brilliant in YAG (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 yag: ahead on 3, level on 1, behind on 4.
Global75, the comparison 83, difference −8
Brilliance68, the comparison 96, difference −28
Fire62, the comparison 54, difference +8
Scintillation72, the comparison 80, difference −8
Spread108, the comparison 100, difference +8
Symmetry100, the comparison 100, difference 0
Shape-norm90, the comparison 103, difference −13
Tilt91, the comparison 78, difference +13
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 Emerald Square Cut gains in YAG
Holds its light better in YAG than in diamond
Tilt 91 against 79 for the Emerald Square Cut in diamond: 12 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 Emerald Square Cut keeps 91 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.
Emerald Square Cut in YAG · Tilt 91
0° · 23% leak
10° · 24% leak
20° · 32% leak
30° · 40% leak
Emerald Square Cut in diamond · Tilt 79
0° · 20% leak
10° · 27% leak
20° · 28% leak
30° · 28% 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.
1.88 ct at 6.5 mm, against 1.46 ct for the same cut in diamond (+29%)
Weight follows specific gravity: 4.55 for YAG against 3.52 for diamond, so the same model at the same size weighs 1.88 ct here and 1.46 ct in diamond, 6.5 mm across. Nothing about the light changes with it.
A Emerald Square Cut 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.
Brilliance 68 against 96 for the T73 Round Brilliant in YAG: 28 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 YAG, whose critical angle is 33.1°, the Emerald Square Cut returns 68 of 100 and the T73 96. The Emerald Square Cut's pavilion mains sit at 28.3°, the T73's at 40.8°. The maps below show where each stone's light returns from and where it leaks.
Emerald Square Cut in YAG · Brilliance 68
T73 Round Brilliant in YAG · Brilliance 96
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 97 for brilliance in YAG, the best of the cuts we score there.
Fire 62 against 84 for the Emerald Square 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 (0.024 in YAG) and counts a ray as fire when the two directions differ by more than 0.6°. The Emerald Square Cut reads 62 against 84 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders YAG'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 Emerald Square Cut in YAG under the sunny-day lighting.
What helps:the DG-Elongated Hexagon reads 93 for fire in YAG, the best of the cuts we score there.
Leakage 23 against 4 for the T73 Round Brilliant in YAG: 19 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 Emerald Square Cut leaks 23% in YAG against 4% for the T73 in YAG. Grey in the maps below is leaking light; the share under each picture is that picture's own.
Emerald Square Cut in YAG · Leakage 23
0° · 23% leak
10° · 24% leak
20° · 32% leak
30° · 40% leak
T73 Round Brilliant in YAG · Leakage 4
0° · 1% leak
10° · 6% leak
20° · 19% leak
30° · 29% 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 3% for leakage in YAG, the best of the cuts we score there.
Pick the Emerald Square Cut in YAG for this: it holds its light better than in diamond when tilted. The catch: it weighs more than in diamond, returns less light than the T73, shows less fire than in diamond and leaks more light than the T73.
If that catch matters more to you, the DG-M5 reads 97 for brilliance in YAG, 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 Emerald Square Cut model we traced.
Emerald Square Cut YAG: questions
Is the Emerald Square a good cut for YAG?
In our census the Emerald Square Cut returns 68 of 100 for brilliance and 62 for fire in YAG, against 96 and 54 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 YAG need?
At least 36.7° for a round design: YAG's critical angle is 33.1°, 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 Emerald Square Cut's pavilion mains sit at 28.3°.
How much does a Emerald Square weigh in YAG?
At 6.5 mm across, 1.88 ct in YAG, against 1.46 ct for the same cut in diamond (+29%): YAG's specific gravity is 4.55, diamond's 3.52.
Can I see the Emerald Square in YAG in 3D?
Yes: the 3D Gemstone Simulator renders it live, with YAG's own refractive index and dispersion. YAG 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 Emerald Square Cut files
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Emerald Square Cut 3D files
The Emerald Square Cut as exact geometry: 49 planar facets, real-world scale, ready for CAD,
rendering, printing and casting.
