Portuguese Bird's Nest Cut Ruby: as much scintillation as any cut we measure
Brilliance 69 · Fire 16 · Scintillation 98 · in our census, where the T73 scores 94 · 37 · 80 in ruby
177 facets in interlocking tiers: in ruby the Portuguese cut sparkles as finely as anything we measure, and gives up most of the fire the diamond version shows.
Rendered in our 3D Gemstone Simulator from the Portuguese Bird's Nest Cut model, 1.00 ct, studio light.
Portuguese Bird's Nest Cut Ruby
Sixteen-fold and tiered five deep on each side of the girdle, the Portuguese cut offsets every tier half a step from the one above it. Our model has 177 facets, a 48.9% table, a shallow 26.0° crown and a 38.0° pavilion.
So many facets give it a scintillation score level with DG-Miliano and DG-Vitruvio, the highest in our ruby census. Fire is another matter: only the Old Single scores less in ruby.
Compared with the T73 Round Brilliant in ruby 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 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.
Against the T73 Round Brilliant in ruby: 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.
Scintillation 98 against 80 for the T73 Round Brilliant in ruby: 18 points higher
Our scintillation score follows the facet plan, and few plans are as busy as this one: the interlocking tiers break the face into many small, shifting reflections. The diamond version scores the same, because the score belongs to the design.
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.
Fire 16 against 65 for the Portuguese Bird's Nest Cut in diamond: 49 points lower
Small facets and a shallow 26.0° crown split little light into colour, and corundum's low dispersion, 0.018 against diamond's 0.044, cuts it further. Even the T73 in ruby shows more, 37.
Portuguese Bird's Nest Cut in ruby · Fire 16
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.
Brilliance 69 against 94 for the T73 Round Brilliant in ruby: 25 points lower
The pavilion, at 38.0°, clears ruby's 36.4° guide minimum, so this is not a window from shallow angles. The light is lost elsewhere in the tiers; our census measures how much, not where.
Portuguese Bird's Nest Cut in ruby · Brilliance 69
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: We have not measured a steeper Portuguese cut; its 38.0° pavilion is already above the 36.4° guide minimum. For the same sparkle with more light, DG-Vitruvio Ruby scores 98 for scintillation and returns 94.
Leakage 30 against 5 for the T73 Round Brilliant in ruby: 25 points higher
The census loses 30% of the light through the back of this design; the T73 in ruby loses 5%, the diamond Portuguese 13%.
Portuguese Bird's Nest Cut in ruby · Leakage 30
0° · 22% leak
10° · 34% leak
20° · 23% leak
30° · 23% leak
T73 Round Brilliant in ruby · Leakage 5
0° · 1% leak
10° · 10% leak
20° · 29% leak
30° · 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.
The Portuguese cut suits a ruby where a busy, glittering face is the point, and a cutter who wants a showpiece for the machine. In ruby it brings the sparkle, not the fire.
For the same scintillation with more light and less leakage, choose a house round: DG-Vitruvio Ruby scores 98 at 94 brilliance, DG-Miliano Ruby 98 at 90.
Portuguese Bird's Nest Cut Ruby: questions
Does a Portuguese cut ruby sparkle?
Yes: Scintillation 98 in our census, level with the best rounds we measure in ruby and above the T73's 80.
How many facets does a Portuguese cut have?
Our model has 177, on a sixteen-fold plan with five tiers above the girdle and five below.
Is a Portuguese cut good for ruby?
For sparkle, yes. For light and fire it trails: Brilliance 69 against 94, Fire 16 against 65 in diamond.
Portuguese cut or DG-Vitruvio for a ruby?
DG-Vitruvio returns more light (94 against 69) and leaks less (6% against 30%), with the same scintillation, 98.
Get the Portuguese Bird's Nest Cut files
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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.
