Diamond Shapes Guide: Size, Sparkle and Which Suits You

Many people pick a diamond shape in a minute and spend weeks on the rest. Shape deserves more time: it decides how big the stone looks, how it sparkles, how much colour it shows and how it must be set. These are the eight shapes you can design with us.

Brilliant or step cut

Seven of the eight are brilliant cuts: many small triangular and kite-shaped facets that break light up into sparkle. That busy pattern also hides small inclusions and a touch of warmth. The emerald is a step cut, with long parallel facets like a staircase. It flashes rather than sparkles, and shows inclusions far more readily.

A round brilliant also hides colour best; the points of ovals, pears and marquises gather it first, and step cuts such as the emerald show it most.

How big each shape looks at 1 ct

Carat is weight, not size: a long shape spreads its weight along the finger, a square one keeps more in depth. These are our designer's face-up sizes, length first; real stones vary a little, so read each as "about". For other weights, see our diamond size chart in carats and mm.

Shape	Cut style	At 1 ct	Ratio
Round	Brilliant	6.5 mm	1.00
Oval	Brilliant	7.7 × 5.7 mm	1.35
Cushion	Brilliant	6.0 mm	1.00
Pear	Brilliant	8.5 × 5.5 mm	1.55
Marquise	Brilliant	10.5 × 5.2 mm	2.02
Emerald	Step	7.0 × 5.0 mm	1.40
Princess	Brilliant	5.5 mm	1.00
Radiant	Brilliant	6.5 × 5.3 mm	1.23

A 1 ct marquise is about 60% longer than a 1 ct round, and a princess is a full millimetre narrower.

Round and cushion

Round

About 6.5 mm across at 1 ct, with 57 or 58 facets arranged for the most light return of any shape. It hides colour and inclusions best. It suits every hand: start with a 1 ct round solitaire in white gold.

Cushion

A square with rounded corners and soft sides, the modern heir to the old mine cut seen in antique rings. Most sparkle in broad flashes, some in a finer crushed-ice glitter, and rounded corners chip less readily than sharp ones. At about 6.0 mm it faces up smaller than a round. It suits slim fingers and vintage taste: try a cushion in a halo.

Oval, pear and marquise

Long shapes make the stone look larger and the finger slimmer. Their quirk is the bow-tie: a darker band across the middle where the centre facets return less light. Most have one; the question is how strong. Reports do not grade it, so judge it by eye or on video.

Oval

Round brilliance in a longer outline. At about 7.7 × 5.7 mm, a ratio of 1.35, it sits in the classic range; past about 1.50 it starts to look narrow. One Dubai jeweller told Gulf News in May 2026 that more than a third of its brides ask for an oval, and it flatters almost any hand, shorter fingers especially. See a 1.5 ct oval in yellow gold.

Pear

One rounded end and one point, traditionally worn with the point towards the fingertip, about 8.5 × 5.5 mm at 1 ct. Check the symmetry: even shoulders, with the point in line with the rounded end. It suits a graceful, less expected look: design a pear in a rose gold halo.

Marquise

The longest shape for its weight, about 10.5 × 5.2 mm at 1 ct, pointed at both ends. It covers the most finger, with strong vintage character, though its bow-tie can be pronounced. It suits a bold hand, and sits naturally on our signature Marquise Shoulders setting, with eight marquise diamonds along the shoulders.

Oval or round?

At 1 ct a round is about 6.5 mm across and an oval about 7.7 mm long, so the oval reads larger and lengthens the finger. The round sparkles more evenly, has no bow-tie and never looks tied to a decade, though it usually costs more at the same grade. For the most light, choose round; for more presence for the weight, choose oval.

Princess, emerald and radiant

Sharp corners and points are where diamonds chip most easily, so each should be covered by a prong or a V-shaped claw, pear and marquise tips included. Ask how they are held before you approve.

Princess

A square brilliant with sharp corners and crisp sparkle. Much of its weight sits in depth, so at about 5.5 mm it is the smallest here, and its four points need protecting. It suits geometric taste and long fingers: try a princess on a pavé band.

Emerald

The step cut: a rectangle with cropped corners, about 7.0 × 5.0 mm at 1 ct. Its large, open facets show inclusions and colour more readily than any brilliant cut, so choose a cleaner, whiter stone than you would for a round. It suits a taste for calm flashes over glitter, and shines in a three-stone emerald ring.

Radiant

An emerald outline with brilliant facets, about 6.5 × 5.3 mm at 1 ct. It hides inclusions far better than an emerald, and its trimmed corners are sturdier than a princess's. It suits anyone who loves the emerald's outline but wants more sparkle: design a radiant solitaire in yellow gold.

Choosing by hand and by habit

• Short or wide fingers: oval, pear or marquise, set lengthways.
• Long, slim fingers: round, cushion or princess, which add width.
• Hands that work hard: round, oval or cushion, with nothing sharp to knock.
• Most sparkle: round first, then the other brilliant cuts such as oval, radiant and princess.

Questions we hear at the counter

Which diamond shape is the most popular? The round brilliant, but only just: in The Knot's 2026 study of US couples, 26% chose a round centre stone and 25% an oval. Ovals and other long shapes are rising fast, in Dubai as elsewhere.

What separates radiant, cushion and princess? All three are brilliant-faceted and can be square. A princess has sharp corners, a cushion rounded corners and curved sides, a radiant straight sides with trimmed corners.

Is the shape written on a grading report? Yes, with the cutting style and measurements in millimetres. Check them against the stone, and any girdle inscription against the report number.

At Mazimo. Design the ring on a hand at true size in our ring designer and send it to us on WhatsApp for the price, or come and see stones and settings at Al Manal Center, Deira, a few minutes' walk from the Gold Souk. Every ring is made in 18K gold, hallmarked in Dubai, and delivered insured across the UAE at no charge.