Old Mine Cut Ruby: a modern round's sparkle, with half the light lost
Brilliance 50 · Fire 36 · Scintillation 81 · in our census, where the T73 scores 94 · 37 · 80 in ruby
A historic cushion, in ruby: Scintillation 81 to the T73's 80, 14% heavier than the same cut in diamond, and 49% of the light lost through the pavilion.
Rendered in our 3D Gemstone Simulator from the Old Mine Cut model, 1.00 ct, studio light.
Old Mine Cut Ruby
A rounder cushion carrying the Peruzzi's facets, with a wide table and a steep pavilion: that is the old mine cut. We modelled it with 74 facets, a broad 60.3% table, a 43.0° crown and a 44.38° pavilion.
In ruby it sits between the other two historic cushions we measure: more light than the Peruzzi, less than the Mazarin. Its sparkle is level with the T73's.
Old Mine cut ruby: worth choosing? Pros and cons
Pros
None by our margins; scintillation runs level with the T73, 81 to 80.
Compared with the T73 Round Brilliant in ruby 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.
All eight scores against the T73
At a glance: the Old Mine 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.
Global62, the comparison 79, difference −17
Brilliance50, the comparison 94, difference −44
Fire36, the comparison 37, difference −1
Scintillation81, the comparison 80, difference +1
Spread98, the comparison 100, difference −2
Symmetry90, the comparison 100, difference −10
Shape-norm78, the comparison 102, difference −24
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.
Only Tilt clears a baseline, 100 against the T73's 75, and on a face returning 50 that is a full share of little light, so it does not count as a pro. Scintillation, 81, is level with the T73's 80. The case for the cut is the look of its broad facets and its place in the history of the brilliant.
The Old Mine's costs in ruby
About half a round's light
Brilliance 50 against 94 for the T73 Round Brilliant in ruby: 44 points lower
Light entering the wide 60.3% table meets a pavilion drawn for diamond's narrower critical angle, and in ruby more of it gets through. Against the same cut in diamond, the ruby returns 50 to 59.
Old Mine Cut in ruby · Brilliance 50
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: Its 44.38° pavilion is above ruby's guide minimum, so a steeper one is not what our data suggests. The Mazarin Cut Ruby gives more light in a historic cushion, 58; the modern Cushion Cut Ruby gives 88.
Leakage 49 against 5 for the T73 Round Brilliant in ruby: 44 points higher
49% of the light in our census leaves through the pavilion, a long way from the T73's 5%. The diamond Old Mine loses 32%.
Old Mine Cut in ruby · Leakage 49
0° · 50% leak
10° · 46% leak
20° · 37% leak
30° · 37% 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.
Fire 36 against 72 for the Old Mine Cut in diamond: 36 points lower
Fire 36 in ruby against 72 in diamond, about level with the T73 in ruby, 37.
Old Mine Cut in ruby · Fire 36
Old Mine Cut in diamond · Fire 72
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: For fire in a ruby that keeps its light, the Trilliant Cut Ruby scores 52.
1.37 ct at 6.5 mm, against 1.21 ct for the same cut in diamond (+14%)
The Old Mine is cut 65.6% deep in diamond and ruby alike, so depth is not the difference. Density is: corundum, at 4.00 against diamond's 3.52, makes a ruby of the same width 14% heavier.
A Old Mine Cut 6.5 mm across, weighed from the model's measured volume and each stone's specific gravity.
Choose the Old Mine in ruby for a reproduction piece or an antique-style setting where the cushion's broad facets matter more than light. Expect a darker face than a modern cut: in our census nearly half the light leaves through the back.
