Brighter dead-on than Tolkowsky’s angles. Less steady the moment the hand moves.
Global score against T57, Tolkowsky’s 1919 ideal, measured the same way in the same material.
Diamondn = 2.417+0.91Ahead
Moissaniten = 2.65+0.11Level
Cubic zirconian = 2.16+0.15Level
−6T57 = 0+6
The short version
Brilliant 73 sits at the same facet count as the T73 reference, so the pair isolates one variable: proportions. It returns more light face-up than the standard does, 94.0% against 92.3%, and finishes only 0.91 ahead of it in diamond, with 0.85 of that margin coming from facet count rather than angles.
Against T73, its like-for-like partner at 73 facets, it is 0.33 behind on angles alone. Brilliance measured dead-on is not the same as performance, and this cut is the clearest illustration of that difference in the registry.
The ledger
Where the points come from
Global is a weighted sum of six terms. Subtract the standard's figure from this cut's,
term by term, and the six differences add back up to the published gap. Nothing is hidden in the total,
so you can see exactly which part of the stone is doing the work.
In diamond n = 2.417
Ahead
89.52 against the standard's 88.61. +0.85 scintillation and +0.58 brilliance, against −0.18 tilt, −0.16 fire and −0.17 leak. The brilliance advantage is real and most of the margin is still facet count.
TermThis cut / standardPoints
Brillianceweight 0.3494.092.3+0.58
Fireweight 0.2078.078.8−0.16
Tiltweight 0.1689.390.4−0.18
Scintillationweight 0.1080.371.8+0.85
Symmetryweight 0.10100.0100.0+0.00
Leakweight 0.10 ↓3.531.88−0.17
Sum of the six terms+0.93
Published Global gap +0.91. The six terms reconstruct it to
0.02 of a point. The difference is rounding in the source figures, not a second method.
In moissanite n = 2.65
Level
89.93 against the standard's 89.82. Level, not a win. Tilt is the whole problem: 88.0 against 93.2, worth −0.83, which cancels the scintillation gain almost exactly.
TermThis cut / standardPoints
Brillianceweight 0.3486.585.3+0.41
Fireweight 0.2095.897.5−0.34
Tiltweight 0.1688.093.2−0.83
Scintillationweight 0.1080.371.8+0.85
Symmetryweight 0.10100.0100.0+0.00
Leakweight 0.10 ↓7.447.76+0.03
Sum of the six terms+0.12
Published Global gap +0.11. The six terms reconstruct it to
0.01 of a point. The difference is rounding in the source figures, not a second method.
In cubic zirconia n = 2.16
Level
91.92 against the standard's 91.77. Level again, and behind T73 at the same facet count, which is the useful comparison here: 91.92 against 92.77, on angles alone.
TermThis cut / standardPoints
Brillianceweight 0.3497.198.0−0.31
Fireweight 0.2084.686.8−0.44
Tiltweight 0.1688.187.1+0.16
Scintillationweight 0.1080.371.8+0.85
Symmetryweight 0.10100.0100.0+0.00
Leakweight 0.10 ↓1.190.51−0.07
Sum of the six terms+0.20
Published Global gap +0.15. The six terms reconstruct it to
0.05 of a point. The difference is rounding in the source figures, not a second method.
What it’s doing
Set Brilliant 73 next to T73, same 73 facets, same scintillation figure and the same 34.5° crown, but a 57% table against 53% and longer stars and lower girdles, and the trade shows in three lines. Brilliance: 94.0 against 92.9, in the modern cut’s favour. Leak: 3.53% against 1.91%, against it. Tilt: 89.3 against 92.2, against it.
It is brighter when you look straight down at it, and it gives more of that back the moment you do not. Against the standard its +0.91 is mostly the +0.85 it banks on facet count; the angles are worth +0.06.
Where it gives ground
Tilt and leak, in every material. It carries the lowest tilt figure of the sub-185 references in diamond (89.3) and in moissanite (88.0), and in moissanite that −0.83 cancels its facet-count gain almost exactly, leaving it level at +0.11.
In cubic zirconia it lands 0.85 behind T73 at identical facet count: proportions alone.
How to read this
The protocol
Monte-Carlo ray census on exact facet geometry: 3,200 rays face-up plus 2,200 at
20° tilt, cosine-weighted from a 7° near-vertical cone. Every cut is scored against Tolkowsky's 1919 ideal,
measured the same way in the same material.
These are engine estimates, ± 2 points, not lab-certified grades.
A lead of under half a point sits inside the engine's resolution, so we don't claim it as a win. A deficit is reported as a deficit, however small.
Scintillation
The one term that is not ray-traced. It is a closed formula on the cut’s active facet count, 100(1 − e−n/45), at a tenth of the weight. Planes buried inside the solid form no facet and are not counted. The standard has 57 facets, fewer than anything else here, so every finely cut stone banks this term before a ray is traced. Each cut page reports its margin with the term removed.
Tilt
A retention figure, the share of face-up return the cut still delivers at 20°, capped at 100. It is a ratio, so read it beside the absolute return rather than on its own: a dim cut has less to lose and keeps a higher share of it.
Symmetry
Reads 100 for every cut, because each is modelled from exact geometry rather than
a finished stone. It contributes nothing to any comparison here: it cancels, and we show the row anyway.
The rest of the registry
Ahead in diamond. Level in moissanite and cubic zirconia.