Cut registry › Historic cuts › Peruzzi
Historic cuts · The triple cut
Fifty-eight facets, in 1700.
The Peruzzi reached the modern facet count three centuries before the modern cut, and our census shows it beating Tolkowsky’s ideal on the one term facet count controls.
The short version
A Peruzzi cut diamond is a cushion-outlined brilliant carrying 58 facets, the same number as a modern round brilliant, and it is also called the triple cut.
It is credited to Vincenzo Peruzzi of Venice in the early 1700s and it is the point at which the facet plan of the modern brilliant was essentially complete.
Definition
Tolkowsky describes it at page 22 of Diamond Design and draws it at figure 10: the cutter "increased the number of facets from sixteen to thirty-two" on the upper side. Thirty-two divides cleanly into 8 bezels, 8 stars and 16 upper girdle halves, which is exactly the modern brilliant crown. One generator covers the Peruzzi, the Old European and the modern round.
That is the striking fact about this cut. The facet arrangement stopped changing around 1700. Everything that happened afterwards was about proportion and about outline, not about where the facets go.
As with the Mazarin, the attribution is traditional. Vincenzo Peruzzi is named everywhere and documented nowhere, and some historians doubt he existed as described. The cut is real; the biography is not established.
Two facet counts, and both are right. The historic count omits the girdle, because a hand-bruted stone had no faceted girdle to count. Our model resolves the girdle as real surfaces, so the census reads 74. Where a figure below depends on facet count, it is the measured number that produced it.
Proportions
Trade description on the left, our reconstruction from figure 10 on the right. It shares its proportion set with the Old Single and the Mazarin on purpose, so that facet count is the only thing that differs between the three.
| Measure | Commonly cited | Our reference stone | What it does |
|---|---|---|---|
| Outline | cushion / soft square | superellipse 3.20 | Squarer than the Mazarin. |
| Historic facets | 58 | 74 measured | The difference is the girdle, sixteen of them. |
| Depth | not standardised | 69.1% | The deepest of the six historic cuts. |
| Table | fig. 10 | 56.8% | Shared with the Old Single and the Mazarin. |
| Pavilion angle | not standardised | 46.2° | Still far steeper than the modern 40.75°. |
Fifty-eight facets is the same count a modern round brilliant carries. If facet count alone decided how a diamond looks, a Peruzzi and a modern brilliant would be the same stone. They are not, and the figures below are the size of the difference.
Light
Measured on the census that runs on every cut on this site: 3,200 rays face-up, 2,200 at 20° tilt, on exact facet geometry, against T57 as the standard.
| Material | Useful light | Leak | Fire | Scintillation | Global | vs the standard |
|---|---|---|---|---|---|---|
| Diamond | 74.99% | 19.24% | 68.40 | 80.69 | 78.49 | −10.11 |
| Moissanite | 71.37% | 14.95% | 94.43 | 80.69 | 83.63 | −6.19 |
| Cubic zirconia | 67.04% | 29.62% | 79.24 | 80.69 | 78.22 | −13.55 |
| T57 standard, diamond | 92.28% | 1.88% | 78.85 | 71.82 | 88.61 | 0.00 |
The Peruzzi beats Tolkowsky’s 1919 ideal on scintillation: 80.69 against 71.82. That is not a fluke and it is not flattery. Scintillation on this engine is a pure function of the number of facets that reach the surface, and this cut carries 74 of them against the standard’s 57. An eighteenth-century cutter reached a denser flash pattern than the 1919 specification, three hundred years early.
It loses everywhere else. 74.99% of useful light against 92.28%, 19.24% of leak against 1.88%, 68.40 of fire against 78.85, for 78.49 Global against 88.61. The facets were right and the angles were wrong, and the angles are worth far more.
Read against the two cuts before it, the point sharpens. Old Single 78.79, Mazarin 74.88, Peruzzi 78.49, on one shared proportion set. Scintillation climbs the whole way. Global does not move. Facet count alone buys sparkle and almost nothing else.
Where the light is: useful return across the face
Five equal bands across the outline. The Peruzzi returns 86.4% at the edges against 69.2% in the centre, so like the single cut it is dark under the table, where a modern round brilliant is flat at 99.1% against 98.1%. A steep pavilion under a wide table sends centre light straight out of the bottom, and no amount of crown faceting fixes it.
Against the standard
Facet count. Level. 74 measured against 57, and 58 against 58 historically. This is the only cut on the site that matches the standard here.
Sparkle. 80.69 against 71.82, and the Peruzzi wins. Its girdle carries sixteen more measured facets than the standard’s knife edge does.
Light return. 74.99% against 92.28%. The gap is the pavilion angle, not the facet plan.
Fire. 68.40 against 78.85.
Outline. A soft square against a true circle, which is the change the Old European made and the one that mattered.
The baseline for all of this is the round brilliant itself. Its facet plan is set out in the anatomy of a round brilliant, and the measured standard we compare against is T57, the stone Tolkowsky published in 1919.
Materials
In moissanite the Peruzzi returns 71.37% for 83.63 Global, with fire at 94.43 against 68.40 in diamond. Moissanite’s higher refractive index suits a steep pavilion better than diamond does, and the leak falls from 19.24% to 14.95%.
In cubic zirconia it returns 67.04% for 78.22 Global. Zirconia’s lower index makes the steep pavilion worse, and leak rises to 29.62%.
That progression is the cleanest demonstration on this page that a facet plan is solved against a refractive index. Watch it in the Index.
Trade-offs
Questions
The questions buyers actually ask, answered in full. Where the answer is ours to prove, the figure is measured on the Index; where it is an established gemological fact, it is stated as one.
A Peruzzi cut diamond, also called the triple cut, is a cushion-outlined brilliant carrying 58 facets. It is credited to Vincenzo Peruzzi of Venice in the early 1700s and it is the point at which the facet plan of the modern round brilliant was essentially complete.
Fifty-eight, the same as a modern round brilliant. Our reconstruction measures 74 facets reaching the surface, the extra sixteen being the girdle, which the historic count does not include.
The Mazarin usually takes that title, as the first with facets on both crown and pavilion. The Peruzzi is the first to reach the modern facet count and the modern crown arrangement: its thirty-two upper-side facets divide into 8 bezels, 8 stars and 16 upper girdle halves, which is exactly a modern brilliant crown.
On scintillation, measurably yes: 80.69 against the 1919 standard’s 71.82, because scintillation on our engine is a pure function of the number of facets reaching the surface and this cut carries 74 against 57. On light return it loses badly, 74.99% against 92.28%.
Its pavilion is far steeper than the modern 40.75 degrees, so a large share of the light entering the table exits through the bottom of the stone rather than returning. We measure 19.24% of leak against the standard’s 1.88%, and the loss concentrates under the table: the centre returns 69.2% against 86.4% at the edges.
Facet count on shared proportions. The Mazarin carries sixteen facets excluding the table on the upper side; the Peruzzi doubled that to thirty-two. Global rises from 74.88 to 78.49 and scintillation from the Mazarin’s figure to 80.69.
The attribution is trade tradition rather than established history. Vincenzo Peruzzi of Venice is named in almost every account of the cut and documented in none of them, and some historians doubt he existed as described. The cut is real; the biography is not established.
In antique jewellery and in museum collections, rarely in the trade. Most surviving examples were recut in the nineteenth and twentieth centuries to modern proportions, because the weight loss was worth the gain in brightness.
Next
See the whole set on the historic cuts index, or the measured house and historic cuts in the cut registry.
Method
Monte-Carlo on exact facet geometry: 3,200 rays face-up plus 2,200 at 20° tilt, cosine-weighted from a 7° near-vertical cone. Useful light is what exits through the crown within 64° of vertical. The same protocol runs on every cut on this site, so the figures are comparable to each other.
They measure our reference geometry for the shape at the proportions listed above, not an average of stones on the market. A peruzzi cut to different proportions will read differently. Treat them as a like-for-like comparison between shapes, not as a grade for any individual stone.
Engine estimates, ±2 points, not lab-certified grades. We do not publish the Index symmetry axis on these pages: it scores facet regularity within each pavilion family, which is meaningful for a round brilliant and misleading for a shape whose pavilion is deliberately irregular.
80.69 here against the standard’s 71.82. The term is 100(1−e−n/45) on the count of facets that actually reach the surface, so it is a pure function of facet count and nothing else.