Brilliance 90 · Fire 46 · Scintillation 85 · in our census, where the T73 scores 78 · 39 · 80 in emerald
Twelve-fold, one pavilion angle, and the most light we measure in emerald: Brilliance 90, with only 10% leaking out of the back.
DG-M5 was drawn for moissanite, on a twelve-fold plan: twenty-four crown mains and twelve stars over a single tier of twenty-four pavilion mains, all at one angle. Our model has 85 facets and a 41.49° pavilion, and stands 60.6% deep.
Emerald is a hard stone to light. Its refractive index is only about 1.58, so its critical angle is 39.4° against diamond's 24.4°, and a pavilion has to stay steep to hold light in. DG-M5's mains sit at 41.49°, above the guide minimum of 39.4°, and in our census it returns more light and leaks less than any other cut we have measured in emerald, rounds and fancy shapes alike.
The catch is the one emerald always brings: little fire, set against the same cut in diamond.
Compared with the T73 Round Brilliant in emerald and with the DG-M5 in diamond. A difference counts from 3 points (Brilliance, Fire, Tilt, Leakage), 5 (Scintillation, Symmetry), 2 (Spread) 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 DG-M5 in emerald (white) against the T73 Round Brilliant in emerald (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 emerald: ahead on 5, level on 2, behind on 1.
0.76 ct at 6.5 mm, against 0.98 ct for the same cut in diamond (−23%)
Beryl is far less dense than diamond, specific gravity 2.72 against 3.52. A DG-M5 6.5 mm across comes to 0.76 ct in emerald and 0.98 ct in diamond.
Try it yourself: Weights in all seven gemstones on the DG-M5 page
Brilliance 90 against 78 for the T73 Round Brilliant in emerald: 12 points higher
Twenty-four pavilion mains at one steep angle give light many chances to strike a facet beyond emerald's 39.4° critical angle and turn back up. The T73, cut to proportions worked out for diamond, returns 78; DG-Anteros comes next at 86.
DG-M5 in emerald · Brilliance 90
T73 Round Brilliant in emerald · Brilliance 78
Try it yourself: Open this Light Return map in the simulator
Leakage 10 against 22 for the T73 Round Brilliant in emerald: 12 points lower
Only 10% of the light in our census leaves through the pavilion, the lowest share of any cut we have measured in emerald. The T73 loses 22%, more than twice as much.
DG-M5 in emerald · Leakage 10
T73 Round Brilliant in emerald · Leakage 22
Try it yourself: Tilt it yourself in the simulator's light map
Scintillation 85 against 80 for the T73 Round Brilliant in emerald: 5 points higher
Scintillation follows the facet plan, and it reads the same in every stone. Twelve-fold symmetry gives DG-M5 85 facets against the T73's 73, so its flashes are slightly finer.
DG-M5 · 85 facets · Scintillation 85
T73 Round Brilliant · 73 facets · Scintillation 80
Try it yourself: Compare the Scintillation spoke in the Cut Performance Wheel
Fire 46 against 67 for the DG-M5 in diamond: 21 points lower
Emerald splits white light into colour weakly: dispersion 0.014, under a third of diamond's 0.044. The same DG-M5 that scores 67 for fire in diamond scores 46 here. Colour, not fire, is what an emerald shows.
DG-M5 in emerald · Fire 46
DG-M5 in diamond · Fire 67
What helps: This is the material. The most fire we measure in emerald is the Oval Cut Emerald at 71, with far less light.
Tilt 64 against 83 for the DG-M5 in diamond: 19 points lower
Tilted by 20°, it keeps 64 of its face-up light; in diamond the same cut keeps 83. Starting from the highest brilliance in emerald, it has more to lose, and one pavilion angle leaves little margin once light arrives at a slant.
DG-M5 in emerald · Tilt 64
DG-M5 in diamond · Tilt 83
What helps: Steepening is not the fix: the mains already sit at 41.49°, above the 39.4° guide minimum. If the stone will be seen at an angle more than face-up, DG-Vitruvio Emerald keeps 78 when tipped, at 78 brilliance.
Try it yourself: Compare the Tilt spoke in the Cut Performance Wheel
For a round emerald where light matters most, DG-M5 is the cut our numbers favour: the highest Brilliance and the lowest leakage of every design we have measured in the stone. It suits a faceter who wants a lively round emerald and accepts that fire stays modest in any cut.
If you want the familiar 73-facet layout, DG-Anteros Emerald comes within a few points. If the stone will hang and swing, the T73 Round Brilliant Emerald holds its light better when tipped. Emeralds are most often step cut; the Emerald Square Cut Emerald page shows what that costs in light.
In our census, DG-M5: Brilliance 90 and 10% leakage, against 86 and 14% for DG-Anteros and 78 and 22% for the T73.
Not for light. Our rectangular Emerald Cut returns 58 in emerald and is not in the stone's top ten; DG-M5 returns 90. The step cut's case rests on the stone's inclusions and brittleness, which we do not measure.
Some: Fire 46, a little above the T73's 39 in emerald, far below 67 for the same cut in diamond.
About 0.76 ct, against 0.98 ct for a diamond of the same width.
The DG-M5 Cut as exact geometry: 85 planar facets, real-world scale, ready for CAD, rendering, printing and casting.
The DG-M5 Cut as a faceting design: 61 + 24 girdles = 85 facets, 96 index, 12-fold mirror-image symmetry, ready for the machine.
Questions before you buy? Email us.
Emerald: optical properties and the top ten cuts · The DG-M5: specifications, model and files