Brilliance 93 · Fire 56 · Scintillation 80 · in our census, where the T73 scores 86 · 50 · 80 in tourmaline
How the DG-Anteros handles light in tourmaline, measured: brilliance 93, fire 56 and 7% leakage, set against the T73 in the same stone and against the same cut in diamond.
Tourmaline has a refractive index of 1.603 to 1.655 and a dispersion of 0.017. Its critical angle, from the low end of that range, is 38.6°, so a round design needs a pavilion of at least 38.6° for head-on light to reflect off both sides of the pavilion and leave through the table. We trace it with one index, 1.629, the midpoint of the published range, and a fire spread of 0.015, 0.86 of the published dispersion. Every picture here is our Light Return tracer at 1.603, and every figure is from the same light census that scores the other gemstones; the 3D Gemstone Simulator shows the DG-Anteros in tourmaline live. Tourmaline is strongly doubly refractive (birefringence up to 0.040), so its back facets can look doubled. Our census traces one index (1.629), so the doubling is not in these figures.
The DG-Anteros has 73 facets, a table of 53.5% of its width and a total depth of 59.4% of its width; its pavilion mains sit at 40.1°. In tourmaline, the census returns 93 of 100 for brilliance and 56 for fire, against 86 and 50 for the T73, our benchmark, in the same stone; the same DG-Anteros in diamond reads 95 and 74.
Compared with the T73 Round Brilliant in tourmaline and with the DG-Anteros 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 DG-Anteros in tourmaline (white) against the T73 Round Brilliant in tourmaline (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 tourmaline: ahead on 5, level on 2, behind on 1.
0.86 ct at 6.5 mm, against 0.97 ct for the same cut in diamond (−11%)
Weight follows specific gravity: 3.13 for tourmaline against 3.52 for diamond, so the same model at the same size weighs 0.86 ct here and 0.97 ct in diamond, 6.5 mm across. Nothing about the light changes with it.
Try it yourself: Weights in every gemstone on the DG-Anteros page
Brilliance 93 against 86 for the T73 Round Brilliant in tourmaline: 7 points higher
Brilliance is the share of the 3,200 census rays that enter the stone and come back out of the crown towards the viewer. In tourmaline, whose critical angle is 38.6°, the DG-Anteros returns 93 of 100 and the T73 86. The DG-Anteros's pavilion mains sit at 40.1°, the T73's at 40.8°. The maps below show where each stone's light returns from and where it leaks.
DG-Anteros in tourmaline · Brilliance 93
T73 Round Brilliant in tourmaline · Brilliance 86
Try it yourself: Open this Light Return map in the simulator
Leakage 7 against 14 for the T73 Round Brilliant in tourmaline: 7 points lower
Leakage is the share of the census rays that enter the stone and leave through the pavilion, or through the crown heading down. The DG-Anteros leaks 7% in tourmaline against 14% for the T73 in tourmaline. Grey in the maps below is leaking light; the share under each picture is that picture's own.
DG-Anteros in tourmaline · Leakage 7
T73 Round Brilliant in tourmaline · Leakage 14
Try it yourself: Tilt it yourself in the simulator's light map
Fire 56 against 74 for the DG-Anteros in diamond: 18 points lower
Fire is the share of the returned light that splits into color at the exit facet: the census traces each exit again at the refractive index minus and plus the fire spread (0.015 in tourmaline) and counts a ray as fire when the two directions differ by more than 0.6°. The DG-Anteros reads 56 against 74 for the same cut in diamond. The figure is the census's; the 3D Gemstone Simulator renders tourmaline's fire live.
The fire figure is the census's, traced at the refractive index minus and plus the fire spread. See the fire in the 3D Gemstone Simulator: the DG-Anteros in tourmaline under the sunny-day lighting.
What helps: the Oval Cut reads 80 for fire in tourmaline, the best of the cuts we score there.
Tilt 69 against 85 for the DG-Anteros in diamond: 16 points lower
Tilt is how much of its face-up brilliance a stone keeps when the census tilts it 20° about its long axis, with 2,200 rays. The DG-Anteros keeps 69 against 85 for the same cut in diamond. The tilt strips below show the maps at 0°, 10°, 20° and 30°, with each picture's own leak share under it.
DG-Anteros in tourmaline · Tilt 69
DG-Anteros in diamond · Tilt 85
What helps: the DG-Miliano reads 86 for tilt in tourmaline, the best of the cuts we score there.
Try it yourself: Compare the Tilt spoke in the Cut Performance Wheel
Pick the DG-Anteros in tourmaline for this: it weighs less than in diamond, returns more light than the T73 and leaks less light than the T73. The catch: it shows less fire than in diamond and loses more light when tilted than in diamond.
If that catch matters more to you, the Oval Cut reads 80 for fire in tourmaline, the best of the cuts we score there.
Every figure on this page is from our light census, traced at one refractive index: a simulation of the geometry, not a grading report. The 3D files and cutting files below are the same DG-Anteros model we traced.
In our census the DG-Anteros returns 93 of 100 for brilliance and 56 for fire in tourmaline, against 86 and 50 for the T73 in the same stone. Against that round and against the same cut in diamond it has 3 pros and 2 cons by our thresholds; the summary above names them.
At least 38.6° for a round design: tourmaline's critical angle is 38.6°, from the low end of its refractive index range, and head-on light has to reflect off both sides of the pavilion and leave through the table. The DG-Anteros's pavilion mains sit at 40.1°.
At 6.5 mm across, 0.86 ct in tourmaline, against 0.97 ct for the same cut in diamond (-11%): tourmaline's specific gravity is 3.13, diamond's 3.52.
Yes: the 3D Gemstone Simulator renders it live, with tourmaline's own refractive index and dispersion. Tourmaline is traced by the same light census as the other gemstones, with its refractive index and fire spread derived from published values, so its scores are on the same scale; the pictures here are our Light Return tracer, and the Cut Performance Wheel sets it against any other cut and stone.
The DG-Anteros Cut as exact geometry: 73 planar facets, real-world scale, ready for CAD, rendering, printing and casting.
The DG-Anteros Cut as a faceting design: 57 + 16 girdles = 73 facets, 96 index, 8-fold mirror-image symmetry, ready for the machine.
Not sure the files open in your software? Get the cube free: the same six formats, for your email address, used only to send them (privacy).
Questions before you buy? Email us.
Tourmaline: optical properties and the top ten cuts · The DG-Anteros: specifications, model and files