Brilliance 67 · Fire 91 · Scintillation 80 · in our census, where the T73 scores 93 · 98 · 80 in strontium titanate
How the Trillion Cut handles light in strontium titanate, measured: brilliance 67, fire 91 and 13% leakage, set against the T73 in the same stone and against the same cut in diamond.
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 Trillion 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 Trillion Cut has 73 facets, a table of 56.6% of its width and a total depth of 50.7% of its width; its pavilion mains sit at 31.9°. In strontium titanate, the census returns 67 of 100 for brilliance and 91 for fire, against 93 and 98 for the T73, our benchmark, in the same stone; the same Trillion Cut in diamond reads 67 and 87.
No figure ahead by our thresholds
Compared with the T73 Round Brilliant in strontium titanate and with the Trillion 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.
At a glance: the Trillion 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 1, level on 2, behind on 5.
Against the T73 in strontium titanate and the same cut in diamond, no figure of the Trillion Cut is ahead by the thresholds above. Its figures are in the wheel and the FAQ; Strontium titanate ranks every cut we score in strontium titanate.
1.16 ct at 6.5 mm, against 0.80 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 1.16 ct here and 0.80 ct in diamond, 6.5 mm across. Nothing about the light changes with it.
Try it yourself: Weights in every gemstone on the Trillion Cut page
Brilliance 67 against 93 for the T73 Round Brilliant in strontium titanate: 26 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 Trillion Cut returns 67 of 100 and the T73 93. The Trillion Cut's pavilion mains sit at 31.9°, the T73's at 40.8°. The maps below show where each stone's light returns from and where it leaks.
Trillion Cut in strontium titanate · Brilliance 67
T73 Round Brilliant in strontium titanate · Brilliance 93
What helps: the DG-M5 reads 97 for brilliance in strontium titanate, the best of the cuts we score there.
Try it yourself: Open this Light Return map in the simulator
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 Trillion 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.
Trillion Cut in strontium titanate · Leakage 13
T73 Round Brilliant in strontium titanate · Leakage 2
What helps: the T105 Round Brilliant reads 1% for leakage in strontium titanate, the best of the cuts we score there.
Try it yourself: Tilt it yourself in the simulator's light map
Fire 91 against 98 for the T73 Round Brilliant in strontium titanate: 7 points lower
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 Trillion Cut reads 91 against 98 for the T73 in strontium titanate. 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 Trillion Cut in strontium titanate under the sunny-day lighting.
What helps: the DG-M5 reads 100 for fire in strontium titanate, the best of the cuts we score there.
Against the T73 in strontium titanate and the same cut in diamond, no figure of the Trillion Cut is ahead by our thresholds. The catch: it weighs more than in diamond, returns less light than the T73, leaks more light than the T73 and shows less fire than the T73.
If that catch matters more to you, the DG-M5 reads 97 for brilliance 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 Trillion Cut model we traced.
In our census the Trillion Cut returns 67 of 100 for brilliance and 91 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 0 pros and 4 cons by our thresholds; the summary above names them.
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 Trillion Cut's pavilion mains sit at 31.9°.
At 6.5 mm across, 1.16 ct in strontium titanate, against 0.80 ct for the same cut in diamond (+46%): strontium titanate's specific gravity is 5.13, diamond's 3.52.
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.
The Trillion Cut as exact geometry: 73 planar facets, real-world scale, ready for CAD, rendering, printing and casting.
The Trillion Cut as a faceting design: 61 + 12 girdles = 73 facets, 120 index, 3-fold symmetry, ready for the machine.
Save with a bundle: the Trillion Cut cutting files are also in Faceter's Classics, 10 cuts for €22.49 until 1 December, then €29.99 (€69.90 as single files). Buy the bundle.
Not sure the files open in your software? Get the cube free: the same six formats, for your email address, used only to send them (privacy).
Questions before you buy? Email us.
Strontium titanate: optical properties and the top ten cuts · The Trillion Cut: specifications, model and files