Square Cut Ruby: a steady square face that starts with less light

Brilliance 78 · Fire 45 · Scintillation 78 · in our census, where the T73 scores 94 · 37 · 80 in ruby

The square counterpart of the round brilliant: in ruby it keeps its light steady when tilted, but starts with less of it.

See it in the simulatorGet the files
The Square Cut in ruby, rendered at an angle in our 3D Gemstone Simulator under studio light
Rendered in our 3D Gemstone Simulator from the Square Cut model, 1.00 ct, studio light.

Square Cut Ruby

Ours carries a full brilliant facet set on a square: 69 facets, a 41.39° pavilion and 65.0% depth.

In ruby it returns 78 for brilliance, well behind the T73, and leaks 16% of the light. It holds what it has when tipped, Tilt 84, but by our rule that counts only for a stone close to the baseline's light.

Square rubies are less common than ovals and cushions, because a square outline wastes more of the flat rough. When one is wanted, the choice is between this brilliant, the cushion, the princess and the step-cut emerald square, and our numbers rank them clearly.

Square cut ruby: good or bad? Pros and cons

Pros

None by our margins. Tilt is high, 84, but on less light.

Cons

Compared with the T73 Round Brilliant in ruby and with the Square Cut 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 ruby (white) against the T73 Round Brilliant in ruby (dashed): solid white where it reaches further, hatched where it falls short. Each pro and con is explained, with pictures, below.

Performance wheel: Square Cut in ruby, against the T73 Round Brilliant in ruby as an outline. Solid white marks where it reaches further, hatching where it falls short. The scores are listed below.50100Global−4Brilliance−16Fire+8Scintillation−2Spread−2Symmetry0Shape-norm0Tilt+9

Against the T73 Round Brilliant in ruby: ahead on 2, level on 2, behind on 4.

  • Global75, the comparison 79, difference −4
  • Brilliance78, the comparison 94, difference −16
  • Fire45, the comparison 37, difference +8
  • Scintillation78, the comparison 80, difference −2
  • Spread98, the comparison 100, difference −2
  • Symmetry100, the comparison 100, difference 0
  • Shape-norm102, the comparison 102, difference 0
  • Tilt84, the comparison 75, difference +9
Face-up light census, a different measure from the Cut Grading Tool; Spread and Shape-norm above 100 sit on the ring.
Open it in the Cut Performance Wheel

What ruby gains in a square cut

We found no score where the square beats the T73 in ruby or the square in diamond by our margins. Tilt, 84 against 75, is the nearest, but with Brilliance 78 it keeps a large share of a smaller amount. Fire is 45, above the T73's 37, yet it is the diamond comparison that counts for fire, and there it loses. What it offers is a crisp square face, steady as it moves.

Where the square cut falls short in ruby

Less fire than a diamond square

Fire 45 against 72 for the Square Cut in diamond: 27 points lower

Fire 45 against 72. In ruby the square sits between the rounds and the elongated cuts for colour.

Square cut in ruby face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 45)

Square Cut in ruby · Fire 45

Square cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 72)

Square Cut in diamond · Fire 72

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.

What helps: Square brilliants sit in the middle for fire; an Oval Cut Ruby ruby reaches 74.

Try it yourself: See the fire in the 3D Gemstone Simulator

Less light than a round ruby

Brilliance 78 against 94 for the T73 Round Brilliant in ruby: 16 points lower

Brilliance 78 against 94. The corners put pavilion facets at angles a round does not have, and some of the light reaching them escapes.

Square cut in ruby face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 78)

Square Cut in ruby · Brilliance 78

T73 round brilliant in ruby face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 94)

T73 Round Brilliant in ruby · 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: Round off the corners and the light comes back: the Cushion Cut Ruby returns 88 in ruby.

Try it yourself: Open this Light Return map in the simulator

Heavier than diamond for its size

1.30 ct at 6.5 mm, against 1.14 ct for the same cut in diamond (+14%)

1.30 ct for a 6.5 mm square in ruby, against 1.14 ct in diamond.

Ruby1.30 ctDiamond1.14 ct
A Square Cut 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.

What helps: Choose by millimetres.

Try it yourself: Weights in all seven gemstones on the Square Cut page

More light lost than through a round

Leakage 16 against 5 for the T73 Round Brilliant in ruby: 11 points higher

16% of the light leaves through the pavilion, against 5% for the T73 in ruby. At 41.39° the pavilion is above the 36.4° guide minimum, so it is not a shallow-pavilion window.

Square Cut in ruby · Leakage 16

Square cut in ruby tilted 0 degrees: Light Return map, 16% of the face leaking0° · 16% leak
Square cut in ruby tilted 10 degrees: Light Return map, 14% of the face leaking10° · 14% leak
Square cut in ruby tilted 20 degrees: Light Return map, 30% of the face leaking20° · 30% leak
Square cut in ruby tilted 30 degrees: Light Return map, 32% of the face leaking30° · 32% leak

T73 Round Brilliant in ruby · Leakage 5

T73 round brilliant in ruby tilted 0 degrees: Light Return map, 1% of the face leaking0° · 1% leak
T73 round brilliant in ruby tilted 10 degrees: Light Return map, 10% of the face leaking10° · 10% leak
T73 round brilliant in ruby tilted 20 degrees: Light Return map, 29% of the face leaking20° · 29% leak
T73 round brilliant in ruby tilted 30 degrees: Light Return map, 30% of the face leaking30° · 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.

What helps: The rounded-corner Cushion Cut Ruby loses 11%, and a smaller square loses the same share as a larger one.

Try it yourself: Tilt it yourself in the simulator's light map

Who a square ruby suits

The square suits a ruby in a geometric setting, or one that will be seen from many angles: it loses little light as it tilts. Face-up, a round ruby is clearly brighter.

For a square outline with more light, the Cushion Cut Ruby; for sharper corners and a little more fire, the Princess Cut Ruby, though it leaks more. A step-cut alternative is the Emerald Square Cut Ruby.

Square Cut Ruby: questions

Is a square cut good for ruby?

It sits mid-table in our ruby census: Brilliance 78 against the T73's 94, and 16% leakage.

Square or princess cut ruby?

The square returns more light (78 against 68) and leaks less (16% against 27%); the princess has a little more fire (52 against 45).

Square or cushion cut ruby?

The cushion, for light: 88 against 78. When it tilts, though, the square keeps more: 84 against 72.

What does a 6.5 mm square ruby weigh?

A square ruby 6.5 mm on a side is around 1.30 ct; the diamond version, 1.14 ct.

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.

  • STEPExact faceted solid for CAD
  • 3DMRhino, closed mesh on its own layer
  • STLWatertight mesh for printing and casting
  • OBJMesh for modelling and rendering
  • FBXBlender, 3ds Max, Maya, Cinema 4D, Unity, Unreal
  • GLBWeb, AR and quick previews
€9.99 · Personal useBuy the 3D files
GemCad64 index

Square Cut cutting files

The Square Cut as a faceting design: 57 + 12 girdles = 69 facets, 64 index, 4-fold mirror-image symmetry, ready for the machine.

  • .ascGemCad design file, 64 index gear
  • .csvTier table: angles, indices and cutting order
  • DiagramPrintable faceting diagram
€9.99 · Personal useBuy the cutting files

Questions before you buy? Email us.

More gemstones and cuts

Ruby: optical properties and the top ten cuts · The Square Cut: specifications, model and files

Other cuts in ruby

The Square Cut in other gemstones