---
title: "Portuguese Bird's Nest Cut Synthetic rutile: Light Scores"
description: "Portuguese Bird's Nest Cut in synthetic rutile: brilliance 80, fire 99, leakage 9%, 4 pros and 2 cons against the T73, from our ray-traced light census."
url: https://digitalgemology.com/gemstones/synthetic-rutile/portuguese-birds-nest
image: https://digitalgemology.com/img/stone-cuts/portuguese-birds-nest-synthetic-rutile-og.jpg?v=fc4eff6c
---

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# Portuguese Bird's Nest Cut Synthetic rutile: more fire in synthetic rutile than in diamond

**Buy (instant download, personal-use license):** [Portuguese Bird's Nest Cut 3D files, €9.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/260cf8a0-6a47-4ff7-91e0-e41657dd7730) · [Portuguese Bird's Nest Cut cutting files, €6.99 · Personal use](https://digitalgemology.lemonsqueezy.com/checkout/buy/57a8bbc7-5d29-4910-9a85-9c0656d946a0) · [Get the cube free](https://digitalgemology.lemonsqueezy.com/checkout/buy/2d1ab55f-2bd6-4897-a4cd-f3320f54e99e)

Brilliance 80 · Fire 99 · Scintillation 98 · in our census, where the T73 scores 81 · 94 · 80 in synthetic rutile

How the Portuguese Bird's Nest Cut handles light in synthetic rutile, measured: brilliance 80, fire 99 and 9% leakage, set against the T73 in the same stone and against the same cut in diamond.

[Get the files](https://digitalgemology.com/gemstones/synthetic-rutile/portuguese-birds-nest#buy) [Open it in the Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=portuguese-birds-nest&stone=synthetic-rutile&ct=1.00&view=angle&lighting=studio&turn=0) [All cuts in synthetic rutile](https://digitalgemology.com/gemstones/synthetic-rutile)

Light Return map of the Portuguese Bird's Nest Cut in synthetic rutile, face-up, from our own tracer at refractive index 2.616. Red, green and blue return light to the eye; gray leaks.

## Portuguese Bird's Nest Cut Synthetic rutile

Synthetic rutile has a refractive index of 2.616 to 2.903 and a dispersion of 0.330. Its critical angle, from the low end of that range, is 22.5°, so a round design needs a pavilion of at least 39.4° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 2.760, the midpoint of the published range, and a fire spread of 0.284, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 2.616, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the Portuguese Bird's Nest Cut in synthetic rutile live. Synthetic rutile is strongly doubly refractive (birefringence 0.287): its two rays have critical angles of 22.5° and 20.1°. Our census traces one index, so every figure for it is a rough approximation.

The Portuguese Bird's Nest Cut has 177 facets, a table of 48.9% of its width and a total depth of 63.1% of its width; its pavilion mains sit at 38.0°. In synthetic rutile, the census returns 80 of 100 for brilliance and 99 for fire, against 81 and 94 for the T73, our benchmark, in the same stone; the same Portuguese Bird's Nest Cut in diamond reads 85 and 65.

## Is synthetic rutile good in a Portuguese Bird's Nest? Pros and cons, measured

### Pros

- [More fire in synthetic rutile than in diamond](https://digitalgemology.com/gemstones/synthetic-rutile/portuguese-birds-nest#pro-fire) 99 vs 65
- [More facets, more sparkle](https://digitalgemology.com/gemstones/synthetic-rutile/portuguese-birds-nest#pro-scint) 98 vs 80
- [Keeps its light when tilted](https://digitalgemology.com/gemstones/synthetic-rutile/portuguese-birds-nest#pro-tiltStab) 100 vs 94
- [Leaks less in synthetic rutile than in diamond](https://digitalgemology.com/gemstones/synthetic-rutile/portuguese-birds-nest#pro-leak) 9 vs 13

### Cons

- [Heavier than the same cut in diamond](https://digitalgemology.com/gemstones/synthetic-rutile/portuguese-birds-nest#con-weight) 1.35 vs 1.11 ct
- [Dimmer in synthetic rutile than in diamond](https://digitalgemology.com/gemstones/synthetic-rutile/portuguese-birds-nest#con-brilliance) 80 vs 85

Compared with the T73 Round Brilliant in synthetic rutile 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](https://digitalgemology.com/about/how-we-measure).

## All eight scores against the T73

At a glance: the Portuguese Bird's Nest Cut in synthetic rutile (white) against the T73 Round Brilliant in synthetic rutile (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 synthetic rutile: ahead on 4, level on 2, behind on 2.

- Global 92, the comparison 88, difference +4
- Brilliance 80, the comparison 81, difference −1
- Fire 99, the comparison 94, difference +5
- Scintillation 98, the comparison 80, difference +18
- Spread 100, the comparison 100, difference 0
- Symmetry 100, the comparison 100, difference 0
- Shape-norm 86, the comparison 87, difference −1
- Tilt 100, the comparison 94, difference +6

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](https://digitalgemology.com/tools/cut-performance-wheel?cut=portuguese-birds-nest&stone=synthetic-rutile); these are the same census figures as our [Cut Performance Index](https://digitalgemology.com/learn/cut-performance-index).

## What the Portuguese Bird's Nest Cut gains in synthetic rutile

### More fire in synthetic rutile than in diamond

**Fire 99** against 65 for the Portuguese Bird's Nest Cut in diamond: 34 points higher

Fire is the share of the returned light that splits into color at the exit facet: the census traces each exit again at the refractive index minus and plus the fire spread (0.284 in synthetic rutile) and counts a ray as fire when the two directions differ by more than 0.6°. The Portuguese Bird's Nest Cut reads 99 against 65 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders synthetic rutile's fire live.

The fire figure is the census's, traced at the refractive index minus and plus the fire spread. [See the fire in the 3D Gemstone Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=portuguese-birds-nest&stone=synthetic-rutile&ct=1.00&view=up&lighting=sun&turn=0): the Portuguese Bird's Nest Cut in synthetic rutile under the sunny-day lighting.

[Try it yourself: See the fire in the 3D Gemstone Simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=portuguese-birds-nest&stone=synthetic-rutile&ct=1.00&view=up&lighting=sun&turn=0)

### More facets, more sparkle

**Scintillation 98** against 80 for the T73 Round Brilliant in synthetic rutile: 18 points higher

Scintillation follows the number of facets the stone shows: 100 × (1 − e^(−facets / 45)). The Portuguese Bird's Nest Cut has 177 facets and the T73 73, so 98 against 80. It depends on the geometry alone, so it is the same in every stone.

*Facet diagram of the Portuguese Bird's Nest Cut: its crown, seen face-up, 177 facets in all*

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

*Facet diagram of the T73 Round Brilliant: its crown, seen face-up, 73 facets in all*

T73 Round Brilliant · 73 facets · Scintillation 80

Scintillation follows the number of facets: more facets, more and smaller flashes as the stone moves. Compare the facet counts under the drawings; each drawing shows only the crown. Drawn from each cut's own model.

[Try it yourself: Compare the Scintillation spoke in the Cut Performance Wheel](https://digitalgemology.com/tools/cut-performance-wheel?cut=portuguese-birds-nest&stone=synthetic-rutile)

### Keeps its light when tilted

**Tilt 100** against 94 for the T73 Round Brilliant in synthetic rutile: 6 points higher

Tilt is how much of its face-up brilliance a stone keeps when the census tilts it 20° about its long axis, with 2,200 rays. The Portuguese Bird's Nest Cut keeps 100 against 94 for the T73. The tilt strips below show the maps at 0°, 10°, 20° and 30°, with each picture's own leak share under it.

Portuguese Bird's Nest Cut in synthetic rutile · Tilt 100

0° · 11% leak

10° · 8% leak

20° · 7% leak

30° · 10% leak

T73 Round Brilliant in synthetic rutile · Tilt 94

0° · 10% leak

10° · 6% leak

20° · 10% leak

30° · 15% 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; gray is leakage. The share under each frame is that picture's own.

[Try it yourself: Compare the Tilt spoke in the Cut Performance Wheel](https://digitalgemology.com/tools/cut-performance-wheel?cut=portuguese-birds-nest&stone=synthetic-rutile)

### Leaks less in synthetic rutile than in diamond

**Leakage 9** against 13 for the Portuguese Bird's Nest Cut in diamond: 4 points lower

Leakage is the share of the census rays that enter the stone and leave through the pavilion, or through the crown heading down. The Portuguese Bird's Nest Cut leaks 9% in synthetic rutile against 13% for the same cut in diamond. Grey in the maps below is leaking light; the share under each picture is that picture's own.

Portuguese Bird's Nest Cut in synthetic rutile · Leakage 9

0° · 11% leak

10° · 8% leak

20° · 7% leak

30° · 10% leak

Portuguese Bird's Nest Cut in diamond · Leakage 13

0° · 13% leak

10° · 8% leak

20° · 8% leak

30° · 8% leak

Each frame is the Light Return map with the stone tilted away from you by the angle shown; gray is leakage. The share under each frame is that picture's own.

[Try it yourself: Tilt it yourself in the simulator's light map](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=portuguese-birds-nest&stone=synthetic-rutile&ct=1.00&view=up&map=1&turn=0)

## What the Portuguese Bird's Nest Cut gives up in synthetic rutile

### Heavier than the same cut in diamond

**1.35 ct** at 6.5 mm, against 1.11 ct for the same cut in diamond (+21%)

Weight follows specific gravity: 4.26 for synthetic rutile against 3.52 for diamond, so the same model at the same size weighs 1.35 ct here and 1.11 ct in diamond, 6.5 mm across. Nothing about the light changes with it.

*Weight of a 6.5 mm Portuguese Bird's Nest Cut: 1.35 ct in synthetic rutile, 1.11 ct in diamond*

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

[Try it yourself: Weights in every gemstone on the Portuguese Bird's Nest Cut page](https://digitalgemology.com/cuts/portuguese-birds-nest#stones)

### Dimmer in synthetic rutile than in diamond

**Brilliance 80** against 85 for the Portuguese Bird's Nest Cut in diamond: 5 points lower

The same cut in diamond returns 85. Synthetic rutile bends light less than diamond: its critical angle is 22.5°, diamond's 24.4°, so a pavilion facet has to be steeper before light reflects off it rather than passing out. The Portuguese Bird's Nest Cut's pavilion returns less of synthetic rutile's light than of diamond's, as the two maps show.

Portuguese Bird's Nest Cut in synthetic rutile · Brilliance 80

Portuguese Bird's Nest Cut in diamond · Brilliance 85

Red, green and blue = light returning to the eye; gray = leakage, light that leaves heading down or stays inside. 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:** [the DG-M5](https://digitalgemology.com/gemstones/synthetic-rutile/dg-m5) reads 97 for brilliance in synthetic rutile, the best of the cuts we score there.

[Try it yourself: Open this Light Return map in the simulator](https://digitalgemology.com/tools/3d_gemstone_simulator?cut=portuguese-birds-nest&stone=synthetic-rutile&ct=1.00&view=up&map=1&turn=0)

## Our verdict on the Portuguese Bird's Nest Cut in synthetic rutile

Pick the Portuguese Bird's Nest Cut in synthetic rutile for this: it shows more fire than in diamond, has more facets to sparkle with, keeps its light when tilted and leaks less than in diamond. The catch: it weighs more than in diamond and returns less light than in diamond.

If that catch matters more to you, [the DG-M5](https://digitalgemology.com/gemstones/synthetic-rutile/dg-m5) reads 97 for brilliance in synthetic rutile, the best of the cuts we score there.

Every figure on this page is from our light census, traced at one refractive index: a simulation of the geometry, not a grading report. The 3D files and cutting files below are the same Portuguese Bird's Nest Cut model we traced.

## Portuguese Bird's Nest Cut Synthetic rutile: questions

### Is the Portuguese Bird's Nest a good cut for synthetic rutile?

In our census the Portuguese Bird's Nest Cut returns 80 of 100 for brilliance and 99 for fire in synthetic rutile, against 81 and 94 for the T73 in the same stone. Against that round and against the same cut in diamond it has 4 pros and 2 cons by our thresholds; the summary above names them.

### What pavilion angle does synthetic rutile need?

At least 39.4° for a round design: synthetic rutile's critical angle is 22.5°, from the low end of its refractive index range, and head-on light has to reflect off both sides of the pavilion and leave through the table. The Portuguese Bird's Nest Cut's pavilion mains sit at 38.0°.

### How much does a Portuguese Bird's Nest weigh in synthetic rutile?

At 6.5 mm across, 1.35 ct in synthetic rutile, against 1.11 ct for the same cut in diamond (+21%): synthetic rutile's specific gravity is 4.26, diamond's 3.52.

### Can I see the Portuguese Bird's Nest in synthetic rutile in 3D?

Yes: the 3D Gemstone Simulator renders it live, with synthetic rutile's own refractive index and dispersion. Synthetic rutile is traced by the same light census as the other gemstones, with its refractive index and fire spread derived from published values, so its scores are on the same scale; the pictures here are our Light Return tracer, and the Cut Performance Wheel sets it against any other cut and stone.

## Get the Portuguese Bird's Nest Cut files

*6 formats* *Millimeters* *Watertight*

### 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.

- **STEP** Exact faceted solid for CAD
- **3DM** Rhino, closed mesh on its own layer
- **STL** Watertight mesh for printing and casting
- **OBJ** Mesh for modeling and rendering
- **FBX** Blender, 3ds Max, Maya, Cinema 4D, Unity, Unreal
- **GLB** Web, AR and quick previews

€9.99 · [Personal use](https://digitalgemology.com/licence) [Buy the 3D files](https://digitalgemology.lemonsqueezy.com/checkout/buy/260cf8a0-6a47-4ff7-91e0-e41657dd7730)

*GemCad* *96 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.

- **.asc** GemCad design file, 96 index gear
- **.csv** Tier table: angles, indices and cutting order
- **Diagram** Printable faceting diagram

€6.99 · [Personal use](https://digitalgemology.com/licence) [Buy the cutting files](https://digitalgemology.lemonsqueezy.com/checkout/buy/57a8bbc7-5d29-4910-9a85-9c0656d946a0)

Not sure the files open in your software? [Get the cube free](https://digitalgemology.lemonsqueezy.com/checkout/buy/2d1ab55f-2bd6-4897-a4cd-f3320f54e99e): the same six formats, for your email address, used only to send them ([privacy](https://digitalgemology.com/privacy#free-sample)).

Questions before you buy? [Email us](mailto:support@digitalgemology.com).

## More gemstones and cuts

[Synthetic rutile: optical properties and the top ten cuts](https://digitalgemology.com/gemstones/synthetic-rutile) · [The Portuguese Bird's Nest Cut: specifications, model and files](https://digitalgemology.com/cuts/portuguese-birds-nest)

### Other cuts in synthetic rutile

- [T73 Round Brilliant](https://digitalgemology.com/gemstones/synthetic-rutile/t73-round-brilliant)
- [T105 Round Brilliant](https://digitalgemology.com/gemstones/synthetic-rutile/t105-round-brilliant)
- [DG-Vitruvio](https://digitalgemology.com/gemstones/synthetic-rutile/dg-vitruvio)
- [DG-Anteros](https://digitalgemology.com/gemstones/synthetic-rutile/dg-anteros)
- [DG-Broken Hearts and Arrows](https://digitalgemology.com/gemstones/synthetic-rutile/dg-broken-hearts-and-arrows)
- [Baguette Cut](https://digitalgemology.com/gemstones/synthetic-rutile/baguette)
- [Emerald Cut](https://digitalgemology.com/gemstones/synthetic-rutile/emerald-cut)
- [Marquise Cut](https://digitalgemology.com/gemstones/synthetic-rutile/marquise)
- [Oval Cut](https://digitalgemology.com/gemstones/synthetic-rutile/oval)
- [Pear Cut](https://digitalgemology.com/gemstones/synthetic-rutile/pear)
- [Radiant Cut](https://digitalgemology.com/gemstones/synthetic-rutile/radiant)
- [Rectangle Cut](https://digitalgemology.com/gemstones/synthetic-rutile/rectangle)
- [Teardrop Cut](https://digitalgemology.com/gemstones/synthetic-rutile/teardrop)
- [Asscher Cut](https://digitalgemology.com/gemstones/synthetic-rutile/asscher)
- [Cushion Cut](https://digitalgemology.com/gemstones/synthetic-rutile/cushion)
- [Emerald Square Cut](https://digitalgemology.com/gemstones/synthetic-rutile/emerald-square)
- [Princess Cut](https://digitalgemology.com/gemstones/synthetic-rutile/princess)
- [Radiant Square Cut](https://digitalgemology.com/gemstones/synthetic-rutile/radiant-square)
- [Square Cut](https://digitalgemology.com/gemstones/synthetic-rutile/square)
- [Triangle Cut](https://digitalgemology.com/gemstones/synthetic-rutile/triangle)
- [Trilliant Cut](https://digitalgemology.com/gemstones/synthetic-rutile/trilliant)
- [Trillion Cut](https://digitalgemology.com/gemstones/synthetic-rutile/trillion)
- [Hexagon Cut](https://digitalgemology.com/gemstones/synthetic-rutile/hexagon)
- [Octagon Cut](https://digitalgemology.com/gemstones/synthetic-rutile/octagon)
- [Old Single Cut](https://digitalgemology.com/gemstones/synthetic-rutile/old-single)
- [Mazarin Cut](https://digitalgemology.com/gemstones/synthetic-rutile/mazarin)
- [Peruzzi Cut](https://digitalgemology.com/gemstones/synthetic-rutile/peruzzi)
- [Old Mine Cut](https://digitalgemology.com/gemstones/synthetic-rutile/old-mine)
- [Old European Cut](https://digitalgemology.com/gemstones/synthetic-rutile/old-european)
- [T57 Round Brilliant](https://digitalgemology.com/gemstones/synthetic-rutile/t57-round-brilliant)
- [DG-M5](https://digitalgemology.com/gemstones/synthetic-rutile/dg-m5)
- [DG-Miliano](https://digitalgemology.com/gemstones/synthetic-rutile/dg-miliano)
- [DG-Rafaello](https://digitalgemology.com/gemstones/synthetic-rutile/dg-rafaello)
- [DG-Bowtie](https://digitalgemology.com/gemstones/synthetic-rutile/dg-bowtie)
- [DG-Elongated Hexagon](https://digitalgemology.com/gemstones/synthetic-rutile/dg-elongated-hexagon)
- [DG-Octagonal Kite](https://digitalgemology.com/gemstones/synthetic-rutile/dg-octagonal-kite)

### The Portuguese Bird's Nest Cut in other gemstones

- [Diamond](https://digitalgemology.com/gemstones/diamond/portuguese-birds-nest)
- [Moissanite](https://digitalgemology.com/gemstones/moissanite/portuguese-birds-nest)
- [Cubic Zirconia](https://digitalgemology.com/gemstones/cubic-zirconia/portuguese-birds-nest)
- [Ruby](https://digitalgemology.com/gemstones/ruby/portuguese-birds-nest)
- [Sapphire](https://digitalgemology.com/gemstones/sapphire/portuguese-birds-nest)
- [Emerald](https://digitalgemology.com/gemstones/emerald/portuguese-birds-nest)
- [Amethyst](https://digitalgemology.com/gemstones/amethyst/portuguese-birds-nest)
- [Topaz](https://digitalgemology.com/gemstones/topaz/portuguese-birds-nest)
- [Spinel](https://digitalgemology.com/gemstones/spinel/portuguese-birds-nest)
- [Demantoid](https://digitalgemology.com/gemstones/demantoid/portuguese-birds-nest)
- [Zircon](https://digitalgemology.com/gemstones/zircon/portuguese-birds-nest)
- [Tourmaline](https://digitalgemology.com/gemstones/tourmaline/portuguese-birds-nest)
- [Peridot](https://digitalgemology.com/gemstones/peridot/portuguese-birds-nest)
- [Tanzanite](https://digitalgemology.com/gemstones/tanzanite/portuguese-birds-nest)
- [YAG](https://digitalgemology.com/gemstones/yag/portuguese-birds-nest)
- [Pyrope](https://digitalgemology.com/gemstones/pyrope/portuguese-birds-nest)
- [Almandine](https://digitalgemology.com/gemstones/almandine/portuguese-birds-nest)
- [Spessartine](https://digitalgemology.com/gemstones/spessartine/portuguese-birds-nest)
- [Grossular](https://digitalgemology.com/gemstones/grossular/portuguese-birds-nest)
- [Chrysoberyl](https://digitalgemology.com/gemstones/chrysoberyl/portuguese-birds-nest)
- [Kunzite](https://digitalgemology.com/gemstones/kunzite/portuguese-birds-nest)
- [Iolite](https://digitalgemology.com/gemstones/iolite/portuguese-birds-nest)
- [Morganite](https://digitalgemology.com/gemstones/morganite/portuguese-birds-nest)
- [GGG](https://digitalgemology.com/gemstones/ggg/portuguese-birds-nest)
- [Strontium titanate](https://digitalgemology.com/gemstones/strontium-titanate/portuguese-birds-nest)