Rendered in our 3D Gemstone Simulator from the Emerald Cut model, 1.00 ct, studio light.
Emerald Cut Ruby
An emerald cut lays its facets in parallel steps around a long table, with the corners cut away. Our model has 57 facets, a 41.0° pavilion and 68.6% total depth, at a length-to-width ratio of 1.5.
In ruby it beats the T73 on two counts: per carat it faces up a few per cent larger, and it shows more fire, 47 against 37. Even so, its fire and tilt fall well short of the diamond emerald cut, and its brilliance and symmetry short of the round.
Face-up, the ruby still returns more light than the same cut in diamond, 65 against 55.
Compared with the T73 Round Brilliant in ruby and with the Emerald 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 Emerald 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 1, behind on 7.
Global61, the comparison 79, difference −18
Brilliance65, the comparison 94, difference −29
Fire47, the comparison 37, difference +10
Scintillation72, the comparison 80, difference −8
Spread96, the comparison 100, difference −4
Symmetry64, the comparison 100, difference −36
Shape-norm85, the comparison 102, difference −17
Tilt55, the comparison 75, difference −20
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.
Face-up size 105 against 100 for the T73 Round Brilliant in ruby (T73 = 100): 5% more face-up area for the same weight
The long table and stepped outline put more of the weight into the face than a round's cone-shaped pavilion does. The gain is small; the rectangle, on nearly the same length-to-width ratio but shallower and with square corners, reaches 121.
Emerald Cut · 7.06 x 4.71 mm at 1.00 ct · Face-up size 105
T73 Round Brilliant · 6.21 mm at 1.00 ct · Face-up size 100
Both stones weigh 1.00 ct in ruby and are drawn to the same scale in millimetres, from each cut's own model. Face-up size is the outline's area per carat, with the T73 at 100: a deeper stone, or a rounder outline, spreads less area for its weight.
Fire 47 against 87 for the Emerald Cut in diamond: 40 points lower
Corundum's dispersion is 0.018, under half of diamond's 0.044, and broad steps give few chances to show what colour there is. Against the round ruby it still wins, 47 to 37; the gap that counts is to diamond.
Emerald Cut in ruby · Fire 47
Emerald Cut in diamond · Fire 87
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: The gap to diamond comes with the material: the census swaps the whole stone, not one property. Among ruby cuts that keep close to the T73's light, the most fire is the Trilliant Cut Ruby at 52, only a few points above this stone.
Symmetry 64 against 100 for the T73 Round Brilliant in ruby: 36 points lower
Step cuts mix long and short steps, so fewer facets repeat exactly. The score is the same in every stone, because it belongs to the design.
Emerald Cut · 57 facets · Symmetry 64
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: It is the design, not a fault. The Asscher Cut Ruby, with concentric square steps, scores 100.
Brilliance 65 against 94 for the T73 Round Brilliant in ruby: 29 points lower
A stepped pavilion returns light in a few broad reflections rather than many crossed ones, and some of what enters the table finds its way out at the back: 25% in our census, against 5% for the T73.
Emerald Cut in ruby · Brilliance 65
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: The pavilion is already 41.0°, above ruby's guide minimum of 36.4°, so a steeper one is not what our data points to. For a step-cut look with more light, the Emerald Square Cut Ruby returns 71; for the most, DG-M5 Ruby returns 100.
Tilt 55 against 83 for the Emerald Cut in diamond: 28 points lower
Tipped by 20°, the ruby keeps a smaller share of its face-up light than the diamond emerald cut. Only the teardrop holds less of it on our ruby pages, 52, and the pear ties at 55.
Emerald Cut in ruby · Tilt 55
0° · 22% leak
10° · 30% leak
20° · 56% leak
30° · 60% leak
Emerald Cut in diamond · Tilt 83
0° · 31% leak
10° · 31% leak
20° · 38% leak
30° · 44% leak
Tilt is how much of its own face-up light a stone keeps when tilted. 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: Of the ruby cuts that stay close to the T73's light, DG-Miliano Ruby keeps the most when tipped, 83.
The emerald cut suits a ruby chosen to show its colour plainly in long steps, set where it is seen mostly face-up. It covers a little more area per carat than a round and returns more light than the same cut in diamond.
