A Guide to Diamond Shapes
Shape is the first thing most people decide and the thing that changes a ring's character most. It also quietly affects price, how large the stone looks, and which clarity grade you can safely buy.
Brilliant cuts
Brilliant cuts use triangular and kite-shaped facets arranged to maximise sparkle. Their busy light return is very good at disguising small inclusions and faint body colour, so you can usually buy a grade or two lower.
- Round — the most brilliant and the most expensive per carat, because more rough is lost in cutting
- Oval — brilliant fire with an elongating shape that looks larger than its weight suggests
- Pear — a teardrop that flatters the finger; check the point is protected by the setting
- Marquise — maximum apparent size for the weight; watch for a dark 'bow-tie' across the centre
- Cushion — softened corners and a warmer, chunkier fire than a round
- Heart and Radiant — brilliant faceting in a distinctive outline
Step cuts
Step cuts use long, parallel facets that produce broad flashes rather than fine sparkle — the 'hall of mirrors' effect. That openness is elegant, but it hides nothing.
Buy step cuts a grade higher in both clarity and colour than you would a brilliant, because inclusions and tint are far easier to see through those open tables.
- Emerald — rectangular with cropped corners; the most architectural of the shapes
- Asscher — a square emerald cut with a deeper, more geometric profile
- Baguette — usually a side stone rather than a centre
Which shapes look biggest
For a fixed carat weight, elongated shapes cover more finger. Marquise, oval, and pear present the largest face-up area; round and princess the smallest. If apparent size matters more than tradition, an oval is the efficient choice.
Length-to-width ratio
For any non-round shape, the ratio between length and width determines whether it reads as classic or dramatic. It is a matter of taste, but there are ranges most people find balanced.
- Oval — 1.30 to 1.50
- Emerald — 1.30 to 1.50
- Pear — 1.45 to 1.75
- Marquise — 1.85 to 2.10
- Cushion and Princess — 1.00 to 1.10 for square, higher for elongated
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