Rendered in our 3D Gemstone Simulator from the Triangle Cut model, 1.00 ct, studio light.
Triangle Cut Ruby
Two crown tiers over three pavilion tiers on an equilateral outline: the triangle keeps its facet set to the bare minimum. Ours has 19 facets, a 60.0% table, a 35.3° crown and a 41.76° pavilion, with 55.4% total depth.
Its pavilion, 41.76°, is steeper than ruby's guide minimum of 36.4°. In our census it has the lowest scintillation of any ruby cut, and it faces up smaller per carat than any of them, 89 against the T73's 100.
Our trilliant, also on a triangle, returns far more light in ruby; the comparison runs through this page.
Triangle cut ruby: is it any good? Pros and cons
Pros
None by our margins. Tilt is high, but on very little light.
Compared with the T73 Round Brilliant in ruby and with the Triangle 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 Triangle 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 3, level on 1, behind on 4.
Global57, the comparison 79, difference −22
Brilliance33, the comparison 94, difference −61
Fire54, the comparison 37, difference +17
Scintillation34, the comparison 80, difference −46
Spread104, the comparison 100, difference +4
Symmetry100, the comparison 100, difference 0
Shape-norm43, the comparison 102, difference −59
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.
Tilt beats both baselines and Fire beats the round ruby, but neither counts as a pro here. Tilt reads 100, against 75 for the T73 and 94 for the diamond triangle, yet a face returning 33 keeps its whole share of very little, so we leave it out. Fire, 54 to the T73's 37, trails diamond by more, which makes it a con. The triangle's offer is simplicity: few facets, each easy to check on the machine.
The triangle's costs in ruby
About a third of a round's light
Brilliance 33 against 94 for the T73 Round Brilliant in ruby: 61 points lower
Few facets give light few ways back to the eye, and much of what enters the wide table meets the pavilion only once. The diamond triangle returns 53; the ruby, 33.
Triangle Cut in ruby · Brilliance 33
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 Trilliant Cut Ruby, also triangular, returns 86, close to the T73. We have not measured a triangle at other angles.
Scintillation follows the number of facets: more facets, more and smaller flashes as the stone moves. Count the facets in each crown. Drawn from each cut's own model.
Leakage 42 against 5 for the T73 Round Brilliant in ruby: 37 points higher
Of the light in our census, 42% escapes through the triangle's pavilion; the T73 lets 5% go. The pavilion is above the critical angle, so this is not light falling straight through.
Triangle Cut in ruby · Leakage 42
0° · 37% leak
10° · 33% leak
20° · 34% leak
30° · 28% 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.
What helps: Shrinking the stone does not change the share. The Trilliant Cut Ruby lets out 12%.
Fire 54 against 86 for the Triangle Cut in diamond: 32 points lower
Ruby beats the round on fire here, 54 to 37, but the diamond triangle scores far more, 86.
Triangle Cut in ruby · Fire 54
Triangle Cut in diamond · Fire 86
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.
The triangle suits a first faceting project, where a small facet set makes every angle easy to check, and small accent stones where light matters less. As a ruby to be looked at closely, it is weak on light and sparkle.
For a triangular ruby, choose the Trilliant Cut Ruby: more light, more sparkle and far less leakage. The Trillion Cut Ruby is a second triangle, at 72 for brilliance.
Triangle Cut Ruby: questions
Is a triangle cut good for ruby?
Poorly, if light matters: it returns 33 to the T73's 94, lets 42% leak and scores 34 for scintillation.
Triangle or trilliant cut ruby?
The trilliant, clearly: Brilliance 86 against 33, scintillation 79 against 34, leakage 12% against 42%.
Is the triangle cut easy to facet?
It has only 19 facets, the fewest of any cut on our ruby pages, which makes it a gentle first design.
What does a 6.5 mm triangle ruby weigh?
Our model puts it at 0.90 ct, and 0.79 ct cut in diamond.
Get the Triangle Cut files
6 formatsMillimetresWatertight
Triangle Cut 3D files
The Triangle Cut as exact geometry: 19 planar facets, real-world scale, ready for CAD,
rendering, printing and casting.
