Brilliance 38 · Fire 22 · Scintillation 81 · in our census, where the T73 scores 72 · 36 · 80 in amethyst
The historic cushion's facet plan scores 81 for sparkle, level with the T73's 80. Its light falls to about half the round's, and its fire to under a third of diamond's.
The old mine cut put the Peruzzi's facets on a rounder cushion, with a wide table and a steep pavilion. We measured a model of 74 facets with a 60.3% table, a 43.0° crown and a 44.38° pavilion.
That pavilion already stands above amethyst's 40.4° guide minimum. Against the same model in diamond, quartz loses most of the fire score (72 to 22); against the T73 in amethyst, it loses light.
Compared with the T73 Round Brilliant in amethyst and with the Old Mine 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 Old Mine Cut in amethyst (white) against the T73 Round Brilliant in amethyst (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 amethyst: ahead on 2, behind on 6.
0.91 ct at 6.5 mm, against 1.21 ct for the same cut in diamond (−25%)
Quartz's density is three quarters of diamond's, 2.65 against 3.52, so an Old Mine of the same millimetres is a quarter lighter in amethyst.
Try it yourself: Weights in all seven gemstones on the Old Mine Cut page
Fire 22 against 72 for the Old Mine Cut in diamond: 50 points lower
Its broad crown facets score 72 for fire in diamond and 22 in quartz. Only three cuts score lower for fire in amethyst.
Old Mine Cut in amethyst · Fire 22
Old Mine Cut in diamond · Fire 72
What helps: If fire counts, the bright DG-Anteros Amethyst scores 54 in quartz.
Brilliance 38 against 72 for the T73 Round Brilliant in amethyst: 34 points lower
The wide table and steep pavilion send part of the light that enters straight down out through the back. In diamond the same model returns 59; in quartz it keeps about two thirds of that.
Old Mine Cut in amethyst · Brilliance 38
T73 Round Brilliant in amethyst · Brilliance 72
What helps: For a cushion that keeps its light, the modern Cushion Cut Amethyst returns 69; for a historic round, the Old European Cut Amethyst 59.
Try it yourself: Open this Light Return map in the simulator
Leakage 62 against 28 for the T73 Round Brilliant in amethyst: 34 points higher
The T73 loses 28% in amethyst. In the picture the round's strip runs from about an eighth grey face-up to over two fifths in its last frame, while the Old Mine's starts near two thirds grey and ends about level with the round's.
Old Mine Cut in amethyst · Leakage 62
T73 Round Brilliant in amethyst · Leakage 28
What helps: Our census holds no steeper Old Mine, and we promise none. The Cushion Cut Amethyst leaks 31% in quartz.
Try it yourself: Tilt it yourself in the simulator's light map
Symmetry 90 against 100 for the T73 Round Brilliant in amethyst: 10 points lower
Symmetry here measures how alike the repeated pavilion facets of a design are. The Old Mine's pavilion facets vary more in size than a modern round's, and its pattern repeats fewer times around the stone.
Old Mine Cut · 74 facets · Symmetry 90
T73 Round Brilliant · 73 facets · Symmetry 100
What helps: The pattern comes with the design. The Old European Cut Amethyst, the round that followed it, scores 100.
Try it yourself: Compare the Symmetry spoke in the Cut Performance Wheel
Choose the Old Mine in amethyst for antique-style and reproduction jewelry, where the broad cushion and its big facets are the reason to buy. It sparkles like a modern round; it does not return as much light.
In amethyst it returns more light than the Peruzzi and less than the Mazarin. For a brighter cushion, the modern Cushion Cut Amethyst; for a historic round, the Old European Cut Amethyst.
For sparkle, yes: 81, a point above the T73's 80. For light, it trails: Brilliance 38 against 72, with 62% leaking.
The modern cushion returns far more light (69 against 38) and leaks half as much (31% against 62%); the Old Mine keeps the historic facet pattern.
The Mazarin returns a little more light (43 against 38) and leaks less; the Old Mine sparkles more (81 against 61).
0.91 ct. The same cushion in diamond: 1.21 ct.
The Old Mine Cut as exact geometry: 74 planar facets, real-world scale, ready for CAD, rendering, printing and casting.
The Old Mine Cut as a faceting design: 58 + 16 girdles = 74 facets, 96 index, 4-fold mirror-image symmetry, ready for the machine.
Questions before you buy? Email us.
Amethyst: optical properties and the top ten cuts · The Old Mine Cut: specifications, model and files