Portuguese Bird's Nest Cut Cubic Zirconia: Pros & Cons

The Portuguese cut is sixteen-fold, with five tiers above the girdle and five below, each offset half a step so the facets interlock like a woven nest. Our model has a 48.9% table, a low 26.0° crown and a 38.0° pavilion, and is 63.1% deep.

That pavilion figure sits right at CZ's guide minimum of 38.1°, and 16% of the light leaks. Whether a steeper pavilion would help we cannot say: we have not measured one.

Tipped, it reads Tilt 100, the top of the scale. From Brilliance 83 that is a share of a smaller amount than the T73 holds, so we do not count it as a pro.

Does cubic zirconia work in a Portuguese Bird's Nest cut?

Pros

Sparkle at the top of our scale 98 vs 80
More fire than the diamond version 79 vs 65

Cons

Heavy for its width 1.84 vs 1.11 ct
Much less light than the T73 in CZ 83 vs 98
About a sixth of the light leaks 16 vs 1

Compared with the T73 Round Brilliant in cubic zirconia and with the Portuguese Bird's Nest 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 Portuguese Bird's Nest Cut in cubic zirconia (white) against the T73 Round Brilliant in cubic zirconia (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 cubic zirconia: ahead on 2, level on 2, behind on 4.

Global88, the comparison 93, difference −5
Brilliance83, the comparison 98, difference −15
Fire79, the comparison 87, difference −8
Scintillation98, the comparison 80, difference +18
Spread100, the comparison 100, difference 0
Symmetry100, the comparison 100, difference 0
Shape-norm90, the comparison 106, difference −16
Tilt100, the comparison 87, difference +13

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 the Bird's Nest gives cubic zirconia

Sparkle at the top of our scale

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

Five interlocking tiers on each side divide the light into far more flashes than the T73's 73 facets can. The crown diagram is dense with small facets.

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

More fire than the diamond version

Fire 79 against 65 for the Portuguese Bird's Nest Cut in diamond: 14 points higher

CZ's 0.060 dispersion, against diamond's 0.044, gives the same flashes more colour. This is fire against diamond, not against the T73 in CZ, which still leads at 87.

Portuguese bird's nest cut in cubic zirconia face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 79) — 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.

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) — 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.

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

The catch with a Bird's Nest CZ

Heavy for its width

1.84 ct at 6.5 mm, against 1.11 ct for the same cut in diamond (+65%)

Deep at 63.1% and in a dense stone: a 6.5 mm Bird's Nest in CZ weighs 1.84 ct, against 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.

What helps: Set and sell it by millimetres.

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

Much less light than the T73 in CZ

Brilliance 83 against 98 for the T73 Round Brilliant in cubic zirconia: 15 points lower

The T73 is close to perfect in CZ, so the gap looks wide; it is also real. With a 26.0° crown and a pavilion at the guide minimum, more light finds a way out than in a modern round.

Portuguese bird's nest cut in cubic zirconia face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 83) — 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.

T73 round brilliant in cubic zirconia face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 98) — 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 the same sparkle score with far more light, DG-Miliano Cubic Zirconia (97) or DG-Vitruvio Cubic Zirconia (98).

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

About a sixth of the light leaks

Leakage 16 against 1 for the T73 Round Brilliant in cubic zirconia: 15 points higher

16% of the light leaves through the pavilion in our census, where the T73 in CZ loses 1%. In diamond this cut loses 13%, so CZ makes it a little worse.

Portuguese bird's nest cut in cubic zirconia tilted 0 degrees: Light Return map, 15% of the face leaking — 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.

Portuguese bird's nest cut in cubic zirconia tilted 10 degrees: Light Return map, 13% of the face leaking — 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: Size does not alter the share. DG-Miliano Cubic Zirconia, with the same facet count, leaks 1%.

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

Who a Bird's Nest CZ suits

Choose it for the pattern itself: a showpiece for the faceting machine, and CZ is a forgiving stone to learn its ten tiers on.

If you want the sparkle and the light, DG-Miliano Cubic Zirconia has the same facet count and returns 97. The Bird's Nest has long been a favourite for coloured stones, where its pattern counts for more than light.

Portuguese Bird's Nest Cut Cubic Zirconia: questions

Does a Portuguese cut sparkle in CZ?

It does: 98 for scintillation, at the top of our scale, where the T73 in CZ scores 80.

Is a Portuguese Bird's Nest CZ bright?

Less than a modern round: Brilliance 83 against 98, with 16% leakage.

Bird's Nest or DG-Miliano in CZ?

Both have 177 facets and the same sparkle score. DG-Miliano returns 97 against 83 and leaks 1% against 16%.

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.

More gemstones and cuts

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

Portuguese Bird's Nest Cut Cubic Zirconia: sparkle at the very top of our scale