Portuguese Bird's Nest Cut Sapphire: sparkle level with the best we measure in this stone

Brilliance 69 · Fire 16 · Scintillation 98 · in our census, where the T73 scores 94 · 37 · 80 in sapphire

177 facets in interlocking rings: in sapphire it sparkles as much as any cut we measure, and keeps very little fire.

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

Portuguese Bird's Nest Cut Sapphire

The Portuguese cut is sixteen-fold, with five crown tiers and five pavilion tiers set half an index step apart, so the facets interlock like a woven nest. We measured a 177-facet model: table 48.9%, crown 26.0°, pavilion 38.0°, depth 63.1%.

In sapphire it ties DG-Miliano and DG-Vitruvio for the highest scintillation in our census. The costs are fire, light, leakage and weight.

Faceters have long chosen it for coloured stones, and to show what a faceting machine can do.

Is the Portuguese cut good for sapphire? Pros and cons

Pros

Cons

Compared with the T73 Round Brilliant in sapphire and with the Portuguese Bird's Nest 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 Portuguese Bird's Nest 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: Portuguese Bird's Nest 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−10Brilliance−25Fire−21Scintillation+18Spread0Symmetry0Shape-norm−27Tilt+25

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

  • Global69, the comparison 79, difference −10
  • Brilliance69, the comparison 94, difference −25
  • Fire16, the comparison 37, difference −21
  • Scintillation98, the comparison 80, difference +18
  • Spread100, the comparison 100, difference 0
  • Symmetry100, the comparison 100, difference 0
  • Shape-norm75, the comparison 102, difference −27
  • 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. 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

What a sapphire gains as a Portuguese cut

As much sparkle as any cut we measure in sapphire

Scintillation 98 against 80 for the T73 Round Brilliant in sapphire: 18 points higher

Scintillation 98 against 80 for the T73. With 177 facets, more than twice the T73's 73, the face breaks into many small flashes as it moves.

Portuguese Bird's Nest Cut · 177 facets · Scintillation 98

T73 Round Brilliant · 73 facets · Scintillation 80

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.

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

The catch with a Portuguese cut sapphire

Little fire, far below the diamond version

Fire 16 against 65 for the Portuguese Bird's Nest Cut in diamond: 49 points lower

Fire 16 against 65 for the same design in diamond. Only the Old Single scores lower in our sapphire census.

Portuguese bird's nest cut in sapphire face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 16)

Portuguese Bird's Nest Cut in sapphire · Fire 16

Portuguese bird's nest cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 65)

Portuguese Bird's Nest Cut in diamond · Fire 65

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: For fire with a round's light, DG-Anteros Sapphire scores 43.

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

Over a quarter less light than the T73

Brilliance 69 against 94 for the T73 Round Brilliant in sapphire: 25 points lower

Brilliance 69 against 94. The same design in diamond returns 85: here sapphire's lower refractive index costs it light. The T73's face-up map beside it is almost entirely colour.

Portuguese bird's nest cut in sapphire face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 69)

Portuguese Bird's Nest Cut in sapphire · Brilliance 69

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: DG-Vitruvio Sapphire matches its sparkle, 98, and returns 94 for light.

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

Six times the T73's leakage

Leakage 30 against 5 for the T73 Round Brilliant in sapphire: 25 points higher

30% of the light in our census leaves through the pavilion; the T73 loses 5% and the diamond version 13%. The pavilion, 38.0°, is already steeper than sapphire's 36.4° guide minimum.

Portuguese Bird's Nest Cut in sapphire · Leakage 30

Portuguese bird's nest cut in sapphire tilted 0 degrees: Light Return map, 22% of the face leaking0° · 22% leak
Portuguese bird's nest cut in sapphire tilted 10 degrees: Light Return map, 34% of the face leaking10° · 34% leak
Portuguese bird's nest cut in sapphire tilted 20 degrees: Light Return map, 23% of the face leaking20° · 23% leak
Portuguese bird's nest cut in sapphire tilted 30 degrees: Light Return map, 23% of the face leaking30° · 23% 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: At 38.0°, the pavilion already clears sapphire's guide minimum, and we have not measured a steeper one. DG-Vitruvio Sapphire leaks 6% with the same sparkle.

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

Heavier than diamond for its width

1.27 ct at 6.5 mm, against 1.11 ct for the same cut in diamond (+14%)

A 6.5 mm stone in this design comes to 1.27 ct, where a diamond would be 1.11 ct. No cut changes that: it is the density of corundum.

Sapphire1.27 ctDiamond1.11 ct
A Portuguese Bird's Nest Cut 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.

What helps: Set and buy it by diameter.

Try it yourself: Weights in all seven gemstones on the Portuguese Bird's Nest Cut page

Who a Portuguese cut sapphire suits

The Portuguese suits a sapphire chosen for glitter across a round face, and a cutter who wants a showpiece. Expect sparkle without much fire, and less light than a modern round.

If you want the same sparkle with more light, DG-Vitruvio Sapphire scores level on scintillation and returns 94; DG-Miliano Sapphire does the same at 90. Cut in diamond, the Portuguese itself keeps far more fire, 65, and more light, 85.

Portuguese Bird's Nest Cut Sapphire: questions

Is a Portuguese cut good for sapphire?

For sparkle, yes: Scintillation 98, joint-highest in our sapphire census. For fire and light, less so: 16 and 69.

How many facets does a Portuguese Bird's Nest cut have?

Our model has 177, against 73 for the T73 Round Brilliant. That count, in sixteen-fold rings, is what lifts its scintillation to 98 in our census.

Portuguese cut or DG-Vitruvio for a sapphire?

They sparkle equally, 98 each. DG-Vitruvio returns more light, 94 against 69, and leaks 6% against 30%.

What does a 6.5 mm Portuguese cut sapphire weigh?

1.27 ct from the model's volume; 1.11 ct in diamond.

Get the Portuguese Bird's Nest Cut files

6 formatsMillimetresWatertight

Portuguese Bird's Nest Cut 3D files

The Portuguese Bird's Nest Cut as exact geometry: 177 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

Portuguese Bird's Nest Cut cutting files

The Portuguese Bird's Nest Cut as a faceting design: 161 + 16 girdles = 177 facets, 96 index, 16-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.

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Sapphire: optical properties and the top ten cuts · The Portuguese Bird's Nest Cut: specifications, model and files

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