Rendered in our 3D Gemstone Simulator from the Peruzzi Cut model, 1.00 ct, studio light.
Peruzzi Cut Ruby
Known also as the triple cut, the Peruzzi splits its crown three ways, into bezels, stars and upper halves, and repeats the scheme under the girdle. Our model has 74 facets, a 56.8% table, a steep 46.0° crown and a 46.22° pavilion, 69.1% deep.
In diamond it is the brightest historic cushion we measure. Ruby treats it worst of the three: its brilliance falls from 75 in diamond to 46, and its leak rises from 19% to 52%.
Peruzzi cut ruby: pros and cons, measured
Pros
None by our margins. Scintillation is level with the T73's, 81 against 80.
Compared with the T73 Round Brilliant in ruby and with the Peruzzi 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 Peruzzi 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, behind on 6.
Global57, the comparison 79, difference −22
Brilliance46, the comparison 94, difference −48
Fire22, the comparison 37, difference −15
Scintillation81, the comparison 80, difference +1
Spread96, the comparison 100, difference −4
Symmetry85, the comparison 100, difference −15
Shape-norm72, the comparison 102, difference −30
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.
We find no pro by our margins. Scintillation, 81 against 80, is level with the T73: with 74 facets the Peruzzi has about as many as a modern round. Tilt reads 100, but on 46 brilliance that is a full share of little light. What it offers is the historic cushion with a modern facet count.
The Peruzzi's costs in ruby
About half the light of a round ruby
Brilliance 46 against 94 for the T73 Round Brilliant in ruby: 48 points lower
Its crown and pavilion are both steep, 46.0° and 46.22°, and in ruby that pairing sends much of the light out of the back rather than up. Of the three historic cushions we measure in ruby, it returns the least.
Peruzzi Cut in ruby · Brilliance 46
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 Peruzzi; its 46.22° pavilion is well above the 36.4° guide minimum. In a historic cushion, the Mazarin Cut Ruby returns 58; in a modern one, the Cushion Cut Ruby 88.
Leakage 52 against 5 for the T73 Round Brilliant in ruby: 47 points higher
52% in our census, against 5% for the T73 and 19% for the same Peruzzi in diamond. Ruby's critical angle, 34.6°, is wider than diamond's, so more light meets a pavilion facet at an angle it can pass through.
Peruzzi Cut in ruby · Leakage 52
0° · 51% leak
10° · 46% leak
20° · 34% leak
30° · 32% 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.
What helps: Every size of Peruzzi leaks the same share. The modern Cushion Cut Ruby lets out 11%.
Fire 22 against 68 for the Peruzzi Cut in diamond: 46 points lower
Even the T73 in ruby beats it, 37 to 22. Small crown facets and corundum's 0.018 dispersion leave little colour to see.
Peruzzi Cut in ruby · Fire 22
Peruzzi Cut in diamond · Fire 68
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.
What helps:DG-Anteros Ruby gives 43 for fire and keeps close to the T73's light.
Symmetry 85 against 100 for the T73 Round Brilliant in ruby: 15 points lower
The design repeats its pavilion facets less evenly than a modern round does. It is a property of the plan, identical in every stone, not a cutting fault.
Peruzzi Cut · 74 facets · Symmetry 85
T73 Round Brilliant · 73 facets · Symmetry 100
Symmetry scores how regular the pavilion facets are within the design. Compare how evenly the facets repeat around each pavilion. Drawn from each cut's own model.
What helps: This is the design. The Old European Cut Ruby keeps a regular pavilion and scores 100.
In ruby the Peruzzi suits a collector who wants the triple cut itself, and its sparkle, more than light. Of the three historic cushions we measure in this stone, it returns the least light and leaks the most.
