The Triangle Diamond
The trillion cut (also called trilliant or trielle) is a triangular diamond with brilliant-cut faceting. Developed in the 1960s by the Asscher brothers, this three-sided shape offers a unique combination of geometric boldness and intense sparkle. With its wide, shallow profile, the trillion displays an impressive face-up size — often appearing 15-25% larger than a round diamond of the same carat weight.
Anatomy of a Trillion
Trillions typically feature 31-50 facets, depending on whether they're cut as modified brilliants or as step-cut triangles. The most common version has:
- Three relatively equal sides — the more equilateral the triangle, the better the symmetry and light performance
- Curved or straight sides: Curved-sided trillions have a softer appearance and return more brilliance. Straight-sided trillions have a more geometric, angular look
- Pointed or rounded corners: Some trillions have sharp points (more dramatic but more vulnerable), while others have slightly rounded corners for durability
Trillion as Center Stone
While trillions are more commonly seen as side stones, they make exceptional center stones for those who want truly unique jewelry:
- Visual impact: The triangular outline is immediately eye-catching — nobody will mistake it for a conventional ring
- Apparent size: The wide, shallow cut creates the largest possible face-up area, making trillions appear significantly larger than their carat weight suggests
- Brilliance: Well-cut trillions display exceptional fire and brilliance due to the wide crown area and brilliant faceting
Center Stone Settings
- V-prong solitaire: Three V-prongs at each corner protect the points while maintaining the geometric purity
- Bezel: A triangular bezel frame echoes the shape while providing complete corner protection
- Halo: A triangular halo of small round diamonds amplifies the trillion's outline
Trillion as Side Stones
The trillion's most common role is as side stones flanking a center diamond. In this capacity, trillions are unmatched:
- They complement round, oval, cushion, and emerald center stones with geometric contrast
- A pair of matched trillions adds significant visual weight and sparkle without overwhelming the center stone
- The triangular shape creates a natural flow from center stone to band, like arrows pointing outward
- They add 0.40-0.80 total carat weight typically (0.20-0.40 each), making the entire ring appear significantly more substantial
Choosing a Trillion
Symmetry
As with all fancy shapes, symmetry is critical. Both sides should be mirror images, all three corners should be equally defined, and the stone should appear as an equilateral (or very nearly equilateral) triangle when viewed face-up.
4Cs
- Color: Match side stone trillions within one color grade of the center stone. For center trillions: G-H in white metals, H-I in warm
- Clarity: VS2-SI1 for side stones (they're small enough to be forgiving). VS2 or higher for center trillions
- Cut: Prioritize symmetry and evenness of the three sides. The trillion should appear perfectly balanced
Corner Protection
Recommended Pieces
- 1 1/2CT Elegance Ring 14k Round/Radiant/Trapezoid White Gold
- Eternal Blush Collection Ladies Ring 1 1/2Ct Round/Emerald 14K
- Ladies Solitaire Ring 3Ct Round 14K White Gold
Like princess and pear cuts, trillion corners are vulnerable to chipping. V-prongs or bezel corners are essential, especially for daily-wear rings. For side stone trillions in three-stone rings, the inner corners are typically protected by their proximity to the center stone's setting, but the outer corners still need V-prongs.