Brighter dead-on than Tolkowsky's angles. Less steady the moment the hand moves.
Global score against Tolkowsky 1919, measured the same way in the same material.
Diamondn = 2.417−2.13Behind
Moissaniten = 2.65−2.93Behind
Cubic zirconian = 2.16−2.67Behind
−3Tolkowsky 1919 = 0+3
The short version
Brilliant 73 sits at the same facet count as the Tolkowsky 73 reference, so the pair isolates one variable: proportions. It returns more light face-up than the standard does (94.0% against 92.6%) and still finishes 2.13 points behind it.
Brightness measured dead-on is not the same as performance. 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
Behind
89.52 against the standard's 91.65. +0.48 for brightness, then −0.51 tilt, −0.14 fire, −0.14 leak and −1.81 scintillation. The brightness advantage is real and is outweighed twice over.
TermThis cut / standardPoints
Useful lightweight 0.3494.092.6+0.48
Fireweight 0.2078.078.7−0.14
Tiltweight 0.1689.392.5−0.51
Scintillationweight 0.1080.398.4−1.81
Symmetryweight 0.10100.0100.0+0.00
Leakweight 0.10 ↓3.532.17−0.14
Sum of the six terms−2.12
Published Global gap −2.13. The six terms reconstruct it to
0.01 of a point. The difference is rounding in the source figures, not a second method.
In moissanite n = 2.65
Behind
89.93 against the standard's 92.86. Tilt is the largest loss after scintillation: 88.0 against 94.0, worth −0.96. Fire slips to 95.8 as well. The widest of its three deficits, at 2.93.
TermThis cut / standardPoints
Useful lightweight 0.3486.586.1+0.14
Fireweight 0.2095.897.2−0.28
Tiltweight 0.1688.094.0−0.96
Scintillationweight 0.1080.398.4−1.81
Symmetryweight 0.10100.0100.0+0.00
Leakweight 0.10 ↓7.447.46+0.00
Sum of the six terms−2.91
Published Global gap −2.93. The six terms reconstruct it to
0.02 of a point. The difference is rounding in the source figures, not a second method.
In cubic zirconia n = 2.16
Behind
91.92 against the standard's 94.59. Behind Tolkowsky 73 at the same facet count, which is the useful comparison here: 91.92 against 92.77, on angles alone.
TermThis cut / standardPoints
Useful lightweight 0.3497.198.4−0.44
Fireweight 0.2084.687.0−0.48
Tiltweight 0.1688.187.1+0.16
Scintillationweight 0.1080.398.4−1.81
Symmetryweight 0.10100.0100.0+0.00
Leakweight 0.10 ↓1.190.58−0.06
Sum of the six terms−2.63
Published Global gap −2.67. The six terms reconstruct it to
0.04 of a point. The difference is rounding in the source figures, not a second method.
What it's doing
Set Brilliant 73 next to Tolkowsky 73, 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. Useful light: 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 than Tolkowsky's proportions do when you don't. Face-up brightness is the condition most easily photographed and most easily specified; it is not the condition a ring is worn in.
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).
In cubic zirconia it finishes 2.67 points behind the standard and 0.85 behind Tolkowsky 73 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.
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
Behind the standard in all three materials. Read the decomposition for why.