Radiant Square Cut Sapphire: a cropped-corner square with less light and fire than a round
Brilliance 76 · Fire 25 · Scintillation 66 · in our census, where the T73 scores 94 · 37 · 80 in sapphire
A square radiant in sapphire keeps a fair share of a round's light and very little of a diamond's fire. By our margins, nothing it does counts as a pro.
Rendered in our 3D Gemstone Simulator from the Radiant Square Cut model, 1.00 ct, studio light.
Radiant Square Cut Sapphire
The radiant square puts a brilliant pavilion under a square with cropped corners. Our model is a deep stone: 49 facets, 72.8% deep, with a 34.64° pavilion figure.
In sapphire it returns 76 for light, a little more than the same cut in diamond. Its weak score is fire: 25, below even the T73 in sapphire, 37.
Its depth also costs size: per carat it faces up smaller than the T73, 91 against 100.
Is a radiant square a good cut for sapphire? Pros and cons
Pros
None by our margins. Its light edges the diamond version's but trails the T73's.
Compared with the T73 Round Brilliant in sapphire and with the Radiant 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 Radiant Square Cut in sapphire (white) against the T73 Round Brilliant in sapphire (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 sapphire: ahead on 2, level on 1, behind on 5.
Global69, the comparison 79, difference −10
Brilliance76, the comparison 94, difference −18
Fire25, the comparison 37, difference −12
Scintillation66, the comparison 80, difference −14
Spread101, the comparison 100, difference +1
Symmetry100, the comparison 100, difference 0
Shape-norm88, the comparison 102, difference −14
Tilt85, the comparison 75, difference +10
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.
None of its scores counts as a pro. Its light beats the diamond version's, 76 against 72, but each score counts once, against the baseline where the gap is wider, and the T73's 94 is the wider gap. Tipped 20°, it keeps 85 of its light to the T73's 75; a tilt figure can be a pro only for a stone within five points of the baseline's brilliance. What it offers is a square with protected corners.
Where the radiant square falls short in sapphire
Far less fire than the diamond radiant square
Fire 25 against 62 for the Radiant Square Cut in diamond: 37 points lower
25 in sapphire, level with DG-Rafaello, against 62 in diamond. Only three cuts we measure in sapphire score lower: the Peruzzi, the Portuguese Bird's Nest and the Old Single.
Radiant Square Cut in sapphire · Fire 25
Radiant Square Cut in diamond · Fire 62
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.
Brilliance 76 against 94 for the T73 Round Brilliant in sapphire: 18 points lower
Brilliance 76 against 94. The pavilion figure, 34.64°, sits just above sapphire's 34.6° critical angle and under its 36.4° guide minimum.
Radiant Square Cut in sapphire · Brilliance 76
T73 Round Brilliant in sapphire · Brilliance 94
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.
What helps: With rounded corners and more light, the Cushion Cut Sapphire returns 88.
Leakage 20 against 5 for the T73 Round Brilliant in sapphire: 15 points higher
In our census one ray in five leaves through the pavilion, 20%, where the T73 lets 5% go. In the T73's strip, the grey is near nothing face-up and grows as it tips.
Radiant Square Cut in sapphire · Leakage 20
0° · 18% leak
10° · 24% leak
20° · 24% leak
30° · 37% leak
T73 Round Brilliant in sapphire · Leakage 5
0° · 1% leak
10° · 10% leak
20° · 29% leak
30° · 30% 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.
Scintillation 66 against 80 for the T73 Round Brilliant in sapphire: 14 points lower
Scintillation 66 against 80, from 49 facets to the T73's 73. Our scintillation score is read from the census model of the cut, not the stone, so the diamond version scores the same, 66.
Scintillation follows the number of facets: more facets, more and smaller flashes as the stone moves. Count the facets in each crown. Drawn from each cut's own model.
The radiant square suits a sapphire set for its outline: a square with protected corners and a fair share of light. It is not a cut for fire.
For more light and sparkle in a cornered stone, choose the Cushion Cut Sapphire. The brightest sapphire in our census is DG-M5 Sapphire. In diamond, the same radiant square has far more fire, 62.
Radiant Square Cut Sapphire: questions
Is a radiant square cut good for sapphire?
Moderately: it returns 76 for light where the T73 returns 94, leaks 20%, and shows little fire (25).
Radiant square or princess for a sapphire?
The radiant square: Brilliance 76 against 68 and leakage 20% against 27%. Fire goes the other way: 52 for the princess, 25 here.
Does a radiant square sapphire look smaller than a round?
Per carat, a little: Face-up size 91 against 100 for the T73. At 6.5 mm across it weighs 1.84 ct.
Get the Radiant Square Cut files
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Radiant Square Cut 3D files
The Radiant Square Cut as exact geometry: 49 planar facets, real-world scale, ready for CAD,
rendering, printing and casting.
