Portuguese Bird's Nest Cut Strontium titanate: more fire in strontium titanate than in diamond
Brilliance 85 · Fire 98 · Scintillation 98 · in our census, where the T73 scores 93 · 98 · 80 in strontium titanate
How the Portuguese Bird's Nest Cut handles light in strontium titanate, measured: brilliance 85, fire 98 and 13% leakage, set against the T73 in the same stone and against the same cut in diamond.
Light Return map of the Portuguese Bird's Nest Cut in strontium titanate, face-up, from our own tracer at refractive index 2.409. Red, green and blue return light to the eye; gray leaks.
Portuguese Bird's Nest Cut Strontium titanate
Strontium titanate has a refractive index of 2.409 and a dispersion of 0.190. Its critical angle, from the low end of that range, is 24.5°, so a round design needs a pavilion of at least 38.9° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 2.409, the midpoint of the published range, and a fire spread of 0.163, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 2.409, 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 strontium titanate live. Strontium titanate has nearly diamond's refractive index (2.409 against 2.417) with about four times its dispersion (0.190 against 0.044): light takes much the same paths as in diamond, and far more of it splits into color.
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 strontium titanate, the census returns 85 of 100 for brilliance and 98 for fire, against 93 and 98 for the T73, our benchmark, in the same stone; the same Portuguese Bird's Nest Cut in diamond reads 85 and 65.
Is strontium titanate good in a Portuguese Bird's Nest? Pros and cons, measured
Compared with the T73 Round Brilliant in strontium titanate 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 strontium titanate (white) against the T73 Round Brilliant in strontium titanate (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 strontium titanate: ahead on 2, level on 3, behind on 3.
Global93, the comparison 94, difference −1
Brilliance85, the comparison 93, difference −8
Fire98, the comparison 98, difference 0
Scintillation98, the comparison 80, difference +18
Spread100, the comparison 100, difference 0
Symmetry100, the comparison 100, difference 0
Shape-norm91, the comparison 100, difference −9
Tilt100, the comparison 92, difference +8
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; these are the same census figures as our Cut Performance Index.
What the Portuguese Bird's Nest Cut gains in strontium titanate
More fire in strontium titanate than in diamond
Fire 98 against 65 for the Portuguese Bird's Nest Cut in diamond: 33 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 (0.163 in strontium titanate) and counts a ray as fire when the two directions differ by more than 0.6°. The Portuguese Bird's Nest Cut reads 98 against 65 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders strontium titanate'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: the Portuguese Bird's Nest Cut in strontium titanate under the sunny-day lighting.
Scintillation 98 against 80 for the T73 Round Brilliant in strontium titanate: 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.
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.
What the Portuguese Bird's Nest Cut gives up in strontium titanate
Heavier than the same cut in diamond
1.62 ct at 6.5 mm, against 1.11 ct for the same cut in diamond (+46%)
Weight follows specific gravity: 5.13 for strontium titanate against 3.52 for diamond, so the same model at the same size weighs 1.62 ct here and 1.11 ct in diamond, 6.5 mm across. Nothing about the light changes with it.
A Portuguese Bird's Nest Cut 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.
Leaks more light than the T73 in strontium titanate
Leakage 13 against 2 for the T73 Round Brilliant in strontium titanate: 11 points higher
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 13% in strontium titanate against 2% for the T73 in strontium titanate. Grey in the maps below is leaking light; the share under each picture is that picture's own.
Portuguese Bird's Nest Cut in strontium titanate · Leakage 13
0° · 13% leak
10° · 8% leak
20° · 8% leak
30° · 7% leak
T73 Round Brilliant in strontium titanate · Leakage 2
0° · 4% leak
10° · 2% leak
20° · 9% leak
30° · 13% 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.
What helps:the T105 Round Brilliant reads 1% for leakage in strontium titanate, the best of the cuts we score there.
Returns less light than the T73 in strontium titanate
Brilliance 85 against 93 for the T73 Round Brilliant in strontium titanate: 8 points lower
Brilliance is the share of the 3,200 census rays that enter the stone and come back out of the crown towards the viewer. In strontium titanate, whose critical angle is 24.5°, the Portuguese Bird's Nest Cut returns 85 of 100 and the T73 93. The Portuguese Bird's Nest Cut's pavilion mains sit at 38.0°, the T73's at 40.8°. The maps below show where each stone's light returns from and where it leaks.
Portuguese Bird's Nest Cut in strontium titanate · Brilliance 85
T73 Round Brilliant in strontium titanate · Brilliance 93
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 reads 97 for brilliance in strontium titanate, the best of the cuts we score there.
Our verdict on the Portuguese Bird's Nest Cut in strontium titanate
Pick the Portuguese Bird's Nest Cut in strontium titanate for this: it shows more fire than in diamond and has more facets to sparkle with. The catch: it weighs more than in diamond, leaks more light than the T73 and returns less light than the T73.
If that catch matters more to you, the T105 Round Brilliant reads 1% for leakage in strontium titanate, 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.
Is the Portuguese Bird's Nest a good cut for strontium titanate?
In our census the Portuguese Bird's Nest Cut returns 85 of 100 for brilliance and 98 for fire in strontium titanate, against 93 and 98 for the T73 in the same stone. Against that round and against the same cut in diamond it has 2 pros and 3 cons by our thresholds; the summary above names them.
What pavilion angle does strontium titanate need?
At least 38.9° for a round design: strontium titanate's critical angle is 24.5°, 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 strontium titanate?
At 6.5 mm across, 1.62 ct in strontium titanate, against 1.11 ct for the same cut in diamond (+46%): strontium titanate's specific gravity is 5.13, diamond's 3.52.
Can I see the Portuguese Bird's Nest in strontium titanate in 3D?
Yes: the 3D Gemstone Simulator renders it live, with strontium titanate's own refractive index and dispersion. Strontium titanate 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
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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.
