Brilliance 100 · Fire 39 · Scintillation 85 · in our census, where the T73 scores 94 · 37 · 80 in ruby
A twelve-fold round drawn for moissanite turns out to be the best light-returner we measure in ruby: Brilliance 100, with nothing escaping through the pavilion.
DG-M5 rings the table with twenty-four crown mains and twelve stars, and cuts the whole pavilion at one angle: 41.49° on our model, with 85 facets and a total depth of 60.6%. There are no upper or lower halves.
We drew it for moissanite and did not expect it to top the ruby census. It does: a single pavilion cone at 41.49° sits five degrees above ruby's guide minimum of 36.4°, and the light that enters the table comes back up.
What corundum cannot supply is fire, and like every ruby round it keeps less of its light at an angle than its diamond twin does.
Compared with the T73 Round Brilliant in ruby 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 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 6, level on 2.
Brilliance 100 against 94 for the T73 Round Brilliant in ruby: 6 points higher
Brilliance 100 is the top of our scale for this stone; the T73 returns 94, DG-Anteros 97. For a red stone that matters more than usual, because returned light is what carries the body colour to the eye.
DG-M5 in ruby · Brilliance 100
T73 Round Brilliant in ruby · Brilliance 94
Try it yourself: Open this Light Return map in the simulator
Scintillation 85 against 80 for the T73 Round Brilliant in ruby: 5 points higher
The twelve-fold crown divides the face into more, narrower facets than the eight-fold T73, and our scintillation score follows the facet plan. The margin is modest: enough to count, not enough to change the character of the stone.
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
Leakage 0 against 5 for the T73 Round Brilliant in ruby: 5 points lower
In our census 0% of the light leaves through the pavilion, against 5% for the T73 in ruby. Every other cut in our ruby census loses something through the back; this one, nothing measurable.
DG-M5 in ruby · Leakage 0
T73 Round Brilliant in ruby · Leakage 5
Try it yourself: Tilt it yourself in the simulator's light map
Fire 39 against 67 for the DG-M5 in diamond: 28 points lower
Same facets, different material: the diamond DG-M5 scores 67 for fire, the ruby 39. Corundum's dispersion of 0.018 is well under half of diamond's 0.044, so the light it returns carries little spectral colour.
DG-M5 in ruby · Fire 39
DG-M5 in diamond · Fire 67
What helps: The twelve-fold plan cannot add dispersion that corundum lacks. A ruby that should flash colour needs a different shape: the Oval Cut Ruby reaches 74, at 66 brilliance.
1.12 ct at 6.5 mm, against 0.98 ct for the same cut in diamond (+14%)
At a specific gravity of 4.00, ruby outweighs diamond by about 14% for identical dimensions: a 6.5 mm DG-M5 is 1.12 ct here and 0.98 ct in diamond.
What helps: Nothing in the cut changes density. Specify the stone by its diameter.
Try it yourself: Weights in all seven gemstones on the DG-M5 page
Tilt 76 against 83 for the DG-M5 in diamond: 7 points lower
Tipped 20°, the ruby keeps 76 of its face-up light where the diamond version keeps 83. A larger critical angle leaves the pavilion fewer directions in which it reflects, and tilting finds the gaps.
DG-M5 in ruby · Tilt 76
DG-M5 in diamond · Tilt 83
What helps: Among the bright rounds in ruby, DG-Miliano Ruby keeps 83 when tipped, with 90 brilliance.
Try it yourself: Compare the Tilt spoke in the Cut Performance Wheel
If a round ruby should return as much light as possible, this is the cut our numbers point to. It leads the ruby census on light and on leakage at once.
For a finer sparkle at nearly the same light, DG-Vitruvio Ruby; for the classic eight-fold look, DG-Anteros Ruby or the T73 Round Brilliant Ruby. Colour flashes are the one thing it cannot give a ruby; for those, see the Oval Cut Ruby.
Ruby is dichroic, purplish red along the crystal's c-axis and orangey red across it, so a round is usually laid out with the table square to that axis to show the purer red face-up. Our census traces a single refractive index, so none of this shows in the scores.
The best we measure: Brilliance 100 against 94 for the T73, and 0% leakage.
Its one-angle pavilion at 41.49° sits comfortably above ruby's guide minimum of 36.4°, so little light finds a way out. We measured both stones separately; neither result was predicted from the other.
Some: Fire 39, a touch above the T73's 37 in ruby, against 67 for the same cut in diamond.
At 6.5 mm across the twelve-fold round weighs 1.12 ct in ruby; cut in diamond it would be 0.98 ct.
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.
Ruby: optical properties and the top ten cuts · The DG-M5: specifications, model and files