Trilliant Cut Diamond: Pros, Cons & Fire

Straight sides and three sharp corners make the trilliant, and jewelers often set it in pairs flanking a centre stone. Its three corners sit on a model of 70 facets, cut 58.9% deep with a 39.0° pavilion.

Against the T73 Round Brilliant in diamond it wins on fire and loses on four scores. Among the three-sided cuts we measure, though, it returns the most light: more than the trillion (67) or the triangle (53).

Is a trilliant a good cut for diamond? Pros and cons

Pros

More fire than the T73 83 vs 78

Compared with the T73 Round Brilliant 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.

All eight scores against the T73

At a glance: the Trilliant Cut in diamond (white) against the T73 Round Brilliant in diamond (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 diamond: ahead on 2, behind on 6.

Global80, the comparison 90, difference −10
Brilliance78, the comparison 93, difference −15
Fire83, the comparison 78, difference +5
Scintillation79, the comparison 80, difference −1
Spread101, the comparison 100, difference +1
Symmetry62, the comparison 100, difference −38
Shape-norm91, the comparison 100, difference −9
Tilt89, the comparison 92, difference −3

Face-up light census, a different measure from the Cut Grading Tool; Spread and Shape-norm above 100 sit on the ring.

Open it in the Cut Performance Wheel

What diamond gains in a trilliant

More fire than the T73

Fire 83 against 78 for the T73 Round Brilliant in diamond: 5 points higher

Fire beats the benchmark by a clear margin. The trilliant's long, angled facets send returning light out in broad flashes, and more of it is split into colour.

Trilliant cut in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 83) — 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.

T73 round brilliant in diamond face-up under a single bright light: a render from our simulator, its coloured flashes are the fire (score 78) — 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.

Try it yourself: See the fire in the 3D Gemstone Simulator

Where the trilliant falls short in diamond

An uneven pavilion

Symmetry 62 against 100 for the T73 Round Brilliant in diamond: 38 points lower

Our symmetry score measures how evenly the pavilion facets repeat within the design, and the trilliant's do not repeat evenly. The trillion, also three-sided, scores 100, so this is the facet plan and not the triangle.

Trilliant Cut · 70 facets · Symmetry 62

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: This is the design. The Trillion Cut Diamond keeps three sides with a pavilion that repeats evenly, Symmetry 100, though it returns less light.

Try it yourself: Compare the Symmetry spoke in the Cut Performance Wheel

Much less light than a round

Brilliance 78 against 93 for the T73 Round Brilliant in diamond: 15 points lower

Corners and straight sides give light more places to escape, and the census returns 78 where the T73 returns 93.

Trilliant cut in diamond face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 78) — 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.

T73 round brilliant in diamond face-up Light Return map: red, green and blue show where the light returns from, grey shows where it leaks (Brilliance 93) — 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: No three-sided cut we measure does better. For more light in a side stone, the Square Cut Diamond returns 85 and DG-Octagonal Kite Diamond 88.

Try it yourself: Open this Light Return map in the simulator

More light lost through the back

Leakage 11 against 2 for the T73 Round Brilliant in diamond: 9 points higher

Light lost through the back comes to 11% for the trilliant in our census and 2% for the T73. The pavilion clears our guide minimum, so the loss is not a shallow-angle window.

Trilliant cut in diamond tilted 0 degrees: Light Return map, 12% of the face leaking — 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.

Trilliant cut in diamond tilted 10 degrees: Light Return map, 16% of the face leaking — 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: Steepening is not the fix: the 39.0° pavilion is already above diamond's 38.9° guide minimum. DG-Octagonal Kite Diamond leaks 7%.

Try it yourself: Tilt it yourself in the simulator's light map

A little less light when tipped

Tilt 89 against 92 for the T73 Round Brilliant in diamond: 3 points lower

The gap is at our threshold: 89 against 92. It is the smallest of the four cons.

Try it yourself: Compare the Tilt spoke in the Cut Performance Wheel

Who a trilliant diamond suits

Choose the trilliant for side stones and graphic designs where a triangle is the point and colour is welcome: it has more fire than the T73 and the most light of our three-sided cuts.

Its sharp corners are best protected in a setting. If you want a three-sided stone with a softer outline and more face for its weight, the Trillion Cut Diamond scores 107 for spread; if light matters more than shape, a round such as the T73 Round Brilliant Diamond.

Trilliant Cut Diamond: questions

Does a trilliant cut diamond have good fire?

Yes: Fire 83 against 78 for the T73 Round Brilliant in our census.

Trilliant or trillion cut diamond?

The trilliant returns more light, 78 against 67; the trillion has more fire (87) and a larger face for its weight.

Why does a trilliant score low on symmetry?

Its pavilion facets do not repeat evenly within the design: Symmetry 62 against 100 for the T73.

What does a 6.5 mm trilliant diamond weigh?

Our trilliant model comes to 0.96 ct at that width.

Get the Trilliant Cut files

6 formatsMillimetresWatertight

Trilliant Cut 3D files

The Trilliant Cut as exact geometry: 72 planar facets, real-world scale, ready for CAD, rendering, printing and casting.

STEPExact faceted solid for CAD
3DMRhino, closed mesh on its own layer
STLWatertight mesh for printing and casting
OBJMesh for modelling and rendering
FBXBlender, 3ds Max, Maya, Cinema 4D, Unity, Unreal
GLBWeb, AR and quick previews

€9.99 · Personal useBuy the 3D files

GemCad96 index

Trilliant Cut cutting files

The Trilliant Cut as a faceting design: 58 + 12 girdles = 70 facets, 96 index, 3-fold mirror-image symmetry, ready for the machine.

.ascGemCad design file, 96 index gear
.csvTier table: angles, indices and cutting order
DiagramPrintable faceting diagram

€9.99 · Personal useBuy the cutting files

Questions before you buy? Email us.

More gemstones and cuts

Diamond: optical properties and the top ten cuts · The Trilliant Cut: specifications, model and files

Trilliant Cut Diamond: more fire than a modern round, on three straight sides