The Cut Guide  ·  Reference Fancy Shape  ·  Brilliant Family
Cut Reference  ·  No. 009

Trillion
Cut

Fancy Brilliant  ·  43–50 Facets

Bold, geometric, and unmistakable — the trillion's triangular outline makes it one of the most visually distinctive cuts in the market. Its pointed corners are also its greatest vulnerability, and most buyers don't know that until it's too late.

The trillion (also called trilliant or triangular brilliant) is a three-sided brilliant cut with either straight or slightly curved sides. Its large table and shallow profile produce exceptional face-up size per carat — trillions consistently look bigger than their weight suggests. The three pointed corners create a graphic, architectural silhouette that reads as modern and intentional. The same corners are prone to chipping and require bezel or v-tip prong protection at every point.

Origin

The trilliant cut was developed and patented by the Asscher family of Amsterdam in the early 20th century, though the modern triangular brilliant as widely sold today evolved through the 1960s and 70s. The name "trillion" was trademarked by Henry Meyer Diamond Company of New York in 1962. Today the term is used generically. The cut appears most often as a side stone flanking a round or cushion center — its triangular silhouette complements many shapes elegantly — but is increasingly chosen as a statement center stone in its own right.

On The Hand
Widening
The trillion's wide, low profile spreads across the finger rather than elongating it. Set with a flat edge toward the base of the finger (pointing up), it creates a bold geometric statement. All three corners need protection — this is not a cut for settings with exposed tips, and it is not recommended for active lifestyles without a bezel.
43–50
Facets
1.00
Ideal L:W Ratio
3
Vulnerable Corners
−20%
vs. Round
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Trillion Cut thecutguide.com
Specifications
Table Percentage
55 – 65%
Larger tables are characteristic of the cut. The wide table maximizes face-up presence but reduces fire. Aim for the middle of this range for the best balance.
Depth Percentage
40 – 48%
Significantly shallower than round brilliants. This is intentional and produces excellent face-up size. Below 38%, stones become windowy; above 50%, the face-up advantage disappears.
Side Profile
Straight / Curved
Straight-sided trillions have a sharper, more graphic look. Curved-side trillions (sometimes called trilliants) produce more brilliance due to a larger effective table. Know which you're buying.
GIA Cut Grade
—
Fancy Shape
No GIA cut grade. Evaluate symmetry grade, face-up photos, and whether all three sides are equal length. Reject anything that looks lopsided.
Polish / Symmetry
Exc / Exc
Both Excellent. Symmetry is especially critical — an uneven trillion reads as a mistake, not a design choice.
Light Performance
Brilliance82
Fire68
Scintillation72
Size per Carat94
Clarity Concealment60

The large table is both the trillion's strength and its limitation — it produces excellent brilliance but exposes inclusions readily. Don't go below VS2 clarity, and inspect face-up photos closely.

Budget
vs. Round Brilliant
−15 to −25%
As center stones, trillions trade at a meaningful discount. Side-stone trillions are often sold in matched pairs at a further discount — but quality varies widely in the side-stone market.
Lab-Grown Trillion
−50 to −65%
Lab-grown trillions offer strong value, particularly as side stones where matched pairs can otherwise be expensive to source in natural.
What Retailers Won't Tell You
⚠ All Three Corners Will Chip Without Protection
The trillion's pointed tips are among the most fragile features in the cut market. Every corner must be protected — bezel, v-tip prong, or a setting specifically designed for the trillion. Many standard prong settings leave the tips exposed. Ask explicitly how each corner is secured before purchasing the setting.
⚠ Clarity Grading Is Less Forgiving Here
The trillion's large, open table acts like a window into the stone. Inclusions that a round's complex facet pattern would mask are visible in a trillion. Don't apply round-brilliant clarity logic here. SI1 in a round might be eye-clean; SI1 in a trillion often isn't. VS2 or better is the practical minimum for center stones.
⚠ Side-Stone Quality Is Frequently Overlooked
Trillions appear most commonly as accent stones flanking a center, and the side-stone market is where quality control is most lax. Mismatched sides — different depths, slightly different outlines, uneven brilliance — are common and rarely disclosed. Compare photos of both sides together before buying a matched pair.
⚠ "Trilliant" vs "Trillion" Are Not the Same
The trilliant has curved sides; the trillion has straight sides. The curved trilliant produces more brilliance and a softer outline. The straight trillion is more graphic and geometric. Retailers frequently use both terms interchangeably. Know which you want and verify with photos — it changes the look of the stone significantly.
The Cut Guide  ·  Assessment  ·  Trillion Cut
"The trillion is the rare cut that looks exactly like it sounds — bold, angular, unapologetically geometric. Its face-up size per carat is exceptional, making it a savvy choice for buyers who want visual impact without carat premium. The caveats are real: clarity must be higher than you'd require for a round, every corner needs protection, and symmetry is non-negotiable. As a side stone it is elegant and versatile; as a center stone it is a statement that rewards deliberate buyers."
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