Peruzzi Cut Sapphire: 74 facets, and half the light out of the back

Brilliance 46 · Fire 22 · Scintillation 81 · in our census, where the T73 scores 94 · 37 · 80 in sapphire

The triple cut sparkles like a modern round in any stone. In sapphire half its light leaves through the pavilion.

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

Peruzzi Cut Sapphire

The Peruzzi's tall 46.0° crown and steep 46.22° pavilion work in diamond, if not brilliantly. In sapphire, whose critical angle is about 34.6°, they let half the light out of the back.

It keeps the sparkle that its 74 facets give: scintillation is level with the T73. Everything we measure about light falls away.

A cutter's first answer to a leaking sapphire is a steeper pavilion. Here the mains are already at 46.22°, about ten degrees past sapphire's guide minimum of 36.4°; the leak comes from light arriving off the axis, which no single steeper angle catches.

Is sapphire good in a Peruzzi cut? Pros and cons

Pros

None that we measure. Scintillation is level with the T73: 81 against 80.

Cons

Compared with the T73 Round Brilliant in sapphire and with the Peruzzi 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 Peruzzi 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.

Performance wheel: Peruzzi Cut in sapphire, against the T73 Round Brilliant in sapphire as an outline. Solid white marks where it reaches further, hatching where it falls short. The scores are listed below.50100Global−22Brilliance−48Fire−15Scintillation+1Spread−4Symmetry−15Shape-norm−30Tilt+25

Against the T73 Round Brilliant in sapphire: ahead on 2, behind on 6.

  • Global57, the comparison 79, difference −22
  • Brilliance46, the comparison 94, difference −48
  • Fire22, the comparison 37, difference −15
  • Scintillation81, the comparison 80, difference +1
  • Spread96, the comparison 100, difference −4
  • Symmetry85, the comparison 100, difference −15
  • Shape-norm72, the comparison 102, difference −30
  • Tilt100, the comparison 75, difference +25
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 sapphire gains in a Peruzzi cut

Neither baseline is beaten on any score. Scintillation is level with the T73 at 81. Tilt reads 100, the share kept of very little light, so it does not count.

Why the Peruzzi struggles in sapphire

Half the T73's light

Brilliance 46 against 94 for the T73 Round Brilliant in sapphire: 48 points lower

The face-up map is mostly grey round a blue centre.

Peruzzi cut in sapphire face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 46)

Peruzzi Cut in sapphire · Brilliance 46

T73 round brilliant in sapphire 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 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: For a sapphire cushion, the modern Cushion Cut returns 88.

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

Half the light leaks

Leakage 52 against 5 for the T73 Round Brilliant in sapphire: 47 points higher

52% in our census against 5% for the T73 in sapphire, and 19% for the same cut in diamond.

Peruzzi Cut in sapphire · Leakage 52

Peruzzi cut in sapphire tilted 0 degrees: Light Return map, 51% of the face leaking0° · 51% leak
Peruzzi cut in sapphire tilted 10 degrees: Light Return map, 46% of the face leaking10° · 46% leak
Peruzzi cut in sapphire tilted 20 degrees: Light Return map, 34% of the face leaking20° · 34% leak
Peruzzi cut in sapphire tilted 30 degrees: Light Return map, 32% of the face leaking30° · 32% leak

T73 Round Brilliant in sapphire · Leakage 5

T73 round brilliant in sapphire tilted 0 degrees: Light Return map, 1% of the face leaking0° · 1% leak
T73 round brilliant in sapphire tilted 10 degrees: Light Return map, 10% of the face leaking10° · 10% leak
T73 round brilliant in sapphire tilted 20 degrees: Light Return map, 29% of the face leaking20° · 29% leak
T73 round brilliant in sapphire 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: Steepening will not help: the mains sit at 46.22°, far above sapphire's 36.4° guide minimum. The Cushion Cut leaks 11%.

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

Little fire

Fire 22 against 68 for the Peruzzi Cut in diamond: 46 points lower

Fire 22, against 68 in diamond: sapphire disperses less than half as strongly, and little light returns to carry colour.

Peruzzi cut in sapphire face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 22)

Peruzzi Cut in sapphire · Fire 22

Peruzzi cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 68)

Peruzzi Cut in diamond · Fire 68

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: The material sets the limit; our best in sapphire is the Oval Cut at 74.

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

A less regular pavilion

Symmetry 85 against 100 for the T73 Round Brilliant in sapphire: 15 points lower

Its pavilion facets are not all the same size, which our symmetry score reads as 85.

Peruzzi Cut · 74 facets · Symmetry 85

T73 Round Brilliant · 73 facets · Symmetry 100

Symmetry scores how regular the pavilion facets are within the design. Compare how evenly the facets repeat around each pavilion. Drawn from each cut's own model.

What helps: It is the design. The Old European Cut Sapphire scores 100.

Try it yourself: Compare the Symmetry spoke in the Cut Performance Wheel

Who a Peruzzi sapphire suits

We would not cut a sapphire as a Peruzzi for brightness. It may suit a dark, saturated stone where the outline is the point.

For a sapphire cushion with light, our modern Cushion Cut; for an antique round, the Old European Cut Sapphire.

As a practice stone for the triple cut in corundum, it teaches the plan; the census says it will not teach brightness.

Peruzzi Cut Sapphire: questions

Is a Peruzzi cut good for sapphire?

Not for light: Brilliance 46 against 94 for the T73 in sapphire, and 52% leakage.

Why does a Peruzzi leak in sapphire but not as much in diamond?

Sapphire's critical angle is about 34.6° against diamond's 24.4°, so light passes out through pavilion facets that would reflect it in diamond: 52% against 19%.

Does a Peruzzi sapphire sparkle?

Yes, as much as a modern round: scintillation 81. It is the light behind the sparkle that is missing.

What does a 6.5 mm Peruzzi sapphire weigh?

Roughly 1.50 ct; the same outline in diamond weighs 1.32 ct.

Get the Peruzzi Cut files

6 formatsMillimetresWatertight

Peruzzi Cut 3D files

The Peruzzi Cut as exact geometry: 74 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
GemCad96 index

Peruzzi Cut cutting files

The Peruzzi Cut as a faceting design: 58 + 16 girdles = 74 facets, 96 index, 4-fold mirror-image symmetry, ready for the machine.

  • .ascGemCad design file, 96 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

Sapphire: optical properties and the top ten cuts · The Peruzzi Cut: specifications, model and files

Other cuts in sapphire

The Peruzzi Cut in other gemstones