What is a trillion cut diamond?
By Jared James · Last updated 21 May 2026
A trillion cut, also called a trilliant, is a triangular-shaped diamond or gemstone with three sides that can be either straight or slightly curved and corners that are typically softened to protect the points from chipping. The facets are arranged in a brilliant pattern to maximise sparkle, and the broad, shallow profile makes the stone appear larger than its carat weight suggests. Trillion cuts are used both as centre stones in rings, where they create a distinctive geometric look, and as side stones flanking a larger centre stone in a three-stone setting.
Loose
Three slightly curved sides and brilliant-style facets.
As side stones
Trillions set as side stones beside a radiant-cut centre.
Frequently asked questions
- Do trillion cut diamonds look larger than other shapes?
- Yes, the trillion's broad, flat profile gives it a larger face-up appearance relative to its carat weight compared with a round brilliant or princess cut. The triangular shape spreads surface area efficiently, so a 0.5 carat trillion typically looks noticeably bigger than a 0.5 carat round.
- Are trillion cut diamonds fragile?
- The three corner points are the most vulnerable areas. Well-cut trillions have slightly rounded or protected corners, and a bezel or V-tip prong setting over each corner gives good protection. In a ring that takes daily wear, protecting those corners is important to prevent chipping.
- What is the difference between a trillion and a trilliant cut?
- The two names refer to essentially the same shape, though in strict usage a trilliant has curved sides giving it a more rounded, fuller appearance, while a trillion has straighter sides. In practice most jewellers and buyers use the names interchangeably, and the distinction has become largely academic.
