Square Cut Diamond: the most light of our square outlines, still short of a round
Brilliance 85 · Fire 72 · Scintillation 78 · in our census, where the T73 scores 93 · 78 · 80 in diamond
The square counterpart of the round brilliant. It returns more light than any other square outline we measure in diamond, and still trails the T73 on four scores.
Rendered in our 3D Gemstone Simulator from the Square Cut model, 1.00 ct, studio light.
Square Cut Diamond
Think of the square brilliant as the round's facet set redrawn on four straight sides, for centre and accent stones alike. In the census it is a 69-facet model, 65.0% deep, with a steep 41.39° pavilion.
We set it against the T73 Round Brilliant. It wins nothing by our margins and loses on brilliance, leakage, fire and tilt. Among squares, though, it leads: the Cushion Cut Diamond returns 80, the Asscher Cut Diamond 69 and the princess 57.
Is a square cut diamond a good choice? Pros and cons
Pros
None by our margins; symmetry and scintillation are level with the T73.
Compared with the T73 Round Brilliant in diamond.
A difference counts from 3 points (Brilliance, Fire, Tilt, Leakage), 5 (Scintillation,
Symmetry), 2 (Spread) 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 Square Cut in diamond (white) against the T73 Round Brilliant in diamond (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 diamond: ahead on 1, level on 1, behind on 6.
Global84, the comparison 90, difference −6
Brilliance85, the comparison 93, difference −8
Fire72, the comparison 78, difference −6
Scintillation78, the comparison 80, difference −2
Spread98, the comparison 100, difference −2
Symmetry100, the comparison 100, difference 0
Shape-norm112, the comparison 100, difference +12
Tilt86, the comparison 92, difference −6
Face-up light census, a different measure from the Cut Grading Tool; Spread and Shape-norm above 100 sit on the ring.
No score beats the T73 by our thresholds. Symmetry is level at 100, and scintillation is close, 78 against 80. What the square offers is its outline, with more light than any other square cut we measure in diamond.
Where the square cut trails the round
Less light than a round
Brilliance 85 against 93 for the T73 Round Brilliant in diamond: 8 points lower
Corners change the paths light takes inside the stone, and some of it never makes it back up: 85 against 93 in our census.
Square Cut in diamond · Brilliance 85
T73 Round Brilliant in diamond · Brilliance 93
Red, green and blue = light returning to the eye; grey = light leaving through the pavilion. 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.
Leakage 10 against 2 for the T73 Round Brilliant in diamond: 8 points higher
A tenth of the light, 10%, escapes through the pavilion; the T73 loses 2%. The pavilion is steep, so this is not light slipping past a shallow angle.
Square Cut in diamond · Leakage 10
0° · 7% leak
10° · 11% leak
20° · 16% leak
30° · 22% leak
T73 Round Brilliant in diamond · Leakage 2
0° · 4% leak
10° · 2% leak
20° · 9% leak
30° · 14% leak
Each frame is the Light Return map with the stone tilted away from you by the angle shown; grey is light leaving through the pavilion. The share under each frame is that picture's own.
What helps: Steepening will not help: at 41.39° the pavilion is already above diamond's 38.9° guide minimum, and the share is the same at any size. DG-Octagonal Kite Diamond loses 7%.
Fire 72 against 78 for the T73 Round Brilliant in diamond: 6 points lower
Fire 72 against 78: what returns carries less colour than a round's light does.
Square Cut in diamond · Fire 72
T73 Round Brilliant in diamond · Fire 78
Look at the coloured flashes: those are fire. Same light, same size, same face-up angle; rendered by our 3D Gemstone Simulator from each cut's own model.
Tilt 86 against 92 for the T73 Round Brilliant in diamond: 6 points lower
At 20° it keeps 86 of its face-up light, against 92 for the T73, so the square darkens a little more as it moves.
Square Cut in diamond · Tilt 86
0° · 7% leak
10° · 11% leak
20° · 16% leak
30° · 22% leak
T73 Round Brilliant in diamond · Tilt 92
0° · 4% leak
10° · 2% leak
20° · 9% leak
30° · 14% 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; grey is light leaving through the pavilion. The share under each frame is that picture's own.
What helps: The Cushion Cut Diamond keeps 92 when tipped, level with the T73, with rounded corners instead of sharp ones.
Choose the square brilliant when the outline must be square and light still matters: no square cut we measure in diamond does better.
If you can move off a strict square, DG-Octagonal Kite Diamond keeps a symmetrical outline with more light and fire. If tilt matters more, the Cushion Cut Diamond. For a step-cut look with a larger face for its weight, the Asscher Cut Diamond, at a large cost in light.
Square Cut Diamond: questions
Is a square cut diamond as brilliant as a round?
No: Brilliance 85 against 93 for the T73, with 10% leakage.
Square or cushion cut diamond?
The square returns more light, 85 against 80; the cushion sparkles more, 85 against 78, and holds its light better when tipped.
Square or princess cut diamond?
The square, by a wide margin in our census: Brilliance 85 against 57 for the princess, and 10% leakage against 18%.
What does a 6.5 mm square cut diamond weigh?
1.14 ct in our model: a square of that width holds more stone than a round.
Get the Square Cut files
6 formatsMillimetresWatertight
Square Cut 3D files
The Square Cut as exact geometry: 69 planar facets, real-world scale, ready for CAD,
rendering, printing and casting.
