Lab-Grown Diamonds · Buying Guide

Diamond Shapes Guide: All 10 Cuts Compared (2026)

By Tushar Leclerc · 9 min read

Last Updated: July 15, 2026

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Choosing between different diamond shapes is the first real decision in buying a ring, and it is the one that changes the look most. Two stones can share a carat weight, a colour grade and a clarity grade and still look nothing alike, because the outline and the faceting are doing completely different jobs. This guide covers all ten shapes: what each one looks like on the hand, how it sparkles, how big it reads for its weight, and what it costs at Riona.

One thing worth settling early. Shape is a preference, not a quality ranking. There is no best diamond shape, only the one that suits the wearer. What follows is the honest trade-off for each, including the drawbacks most jewellers skip.

Shape vs cut: what is the difference?

The two words get used interchangeably, which causes real confusion when you are shopping. They are not the same thing.

Shape is the outline of the stone viewed from above: round, square, oval, teardrop. It is geometry, and it is a matter of taste.

Cut is how well the stone was faceted and finished: the proportions, the symmetry, the polish. Cut is graded from Excellent to Poor and it is the single biggest driver of how alive a diamond looks. A poorly cut round will be outshone by a well-cut oval every time.

So when someone says "most popular diamond cuts" they usually mean shapes. Both matter, but only one of them is graded on your certificate. Our guide to the 4Cs covers how cut is measured.

Facet style is the third piece. Brilliant cuts (round, oval, pear, marquise, cushion, radiant, heart, princess) use triangular and kite-shaped facets to scatter light into sparkle. Step cuts (emerald, asscher) use long parallel planes that produce broad flashes instead. That difference explains most of what follows.

The 10 different diamond shapes

Each shape below links to the matching collection if you want to see the stones themselves. Prices are the live starting price at Riona for that shape in lab-grown.

1. Round brilliant

The round brilliant accounts for most engagement rings sold, and it earns that on physics rather than fashion. Its 57 or 58 facets were mathematically worked out to return as much light to the eye as possible, so a round reads brighter than anything else at the same colour and clarity. It is also forgiving: the faceting scatters light so hard that small inclusions hide well, meaning a lower clarity grade still looks eye-clean.

The catch is cost. Cutting a round wastes more of the original crystal than any other shape, so you pay the most per carat. Our round engagement rings start at $592.

2. Oval

An oval is a round that has been stretched, and the stretch does two useful things: it spreads the same carat weight over a longer surface, so it looks roughly 10% larger than a round of identical weight, and its long axis lengthens the finger. That combination is why ovals are the most requested alternative to round.

Watch for the bow-tie, a dark band across the centre caused by facets shadowing the middle. Every oval has one to some degree; on a well-cut stone you have to look for it. See oval engagement rings from $575.

3. Princess

The princess is the square brilliant: sharp geometric outline, brilliant faceting inside. It keeps far more of the rough crystal than a round, which is why it costs noticeably less per carat while still throwing serious sparkle.

The trade-off is the corners. Four sharp points are the most vulnerable part of any diamond, so a princess wants a setting with protected corners rather than exposed prongs. Our princess cut engagement rings start at $903.

4. Emerald

An emerald cut is a step cut, and that single fact explains everything about it. Long parallel planes cut in steps down from the table produce broad flashes of light rather than fire, an effect people describe as a hall of mirrors. Anyone choosing an emerald is choosing it deliberately over a round; the two are trying to do opposite things.

Be honest about the trade-off: those open planes are a window into the stone, so inclusions and colour tints that a round would hide are visible here. Clarity matters more in an emerald than in any other shape. Browse emerald cut engagement rings from $841.

5. Cushion

A cushion is a rounded square with an antique lineage, descended from the old mine cuts of the 1800s. Its facets are larger than a round's, which gives a softer, more watery fire instead of crisp white sparkle. It is the shape for someone who finds a round too clinical.

Cushions hold colour a little more visibly than rounds, so if you want an icy white look, go a grade higher on colour. See cushion cut engagement rings from $945.

6. Pear

A pear is half round brilliant, half marquise: one rounded end, one point. It elongates the finger like an oval but with more character, and it is traditionally worn with the point toward the fingernail.

Symmetry is everything in a pear. The two shoulders must mirror each other, and an off-centre point is obvious once you see it. The point also needs protecting. Our pear shaped engagement rings start at $892.

7. Marquise

The marquise has the largest surface area per carat of any shape, which means it looks bigger for the weight than anything else on this list. If maximum visual size for the budget is the goal, this is the answer.

It has two points instead of one, so it needs the most careful setting, and the bow-tie effect can be pronounced. Cut quality matters more here than average. See marquise engagement rings from $768.

8. Radiant

A radiant is the compromise shape: emerald's rectangular outline with brilliant faceting inside. You get the elongated silhouette without the clarity exposure of a step cut, because the brilliant facets hide inclusions the way a round does.

Radiants are less common than the shapes above, which is part of the appeal for some buyers. Browse radiant cut engagement rings from $980.

9. Asscher

An asscher is a square step cut with cropped corners, cut in concentric squares that create a distinctive hall-of-mirrors depth. It is the most Art Deco shape here, and like the emerald it shows clarity, so pay for a higher grade.

It also reads smaller than its carat weight, because the depth carries weight you cannot see from above. See asscher cut engagement rings from $975.

10. Heart

The heart is the hardest shape to cut well. Symmetry is everything: the lobes must match, the cleft must be sharp, the point must line up. Below about one carat the shape gets hard to read on the finger, so this is a shape that wants some size.

It is unmistakably romantic and unmistakably a statement. Our heart shaped engagement rings start at $862.

Round SolitaireFrom $1,369 Oval Pave BandFrom $1,369 Princess SolitaireFrom $1,120 Emerald Split-ShankFrom $1,378 Cushion SolitaireFrom $1,369

Diamond shapes and cuts compared

Every stone in that table is IGI-certified and graded on the same 4Cs scale used for mined diamonds, because a lab-grown diamond is the same material: pure carbon, Mohs hardness 10, identical refractive index. If you want the full comparison, read lab-grown vs natural diamonds.

Which shape looks biggest for the carat?

Carat is weight, not size, and where a cutter puts that weight decides how big the stone reads from above. Shapes that spread their weight across the top look larger; shapes that carry depth look smaller.

• Largest for the weight: marquise, then oval and pear. All three are elongated, so they cover more finger.
• Middle: emerald and radiant read larger than round; princess and heart are close to round.
• Smallest for the weight: asscher and cushion, which hold weight in their depth.

The practical version: a 1.5 carat marquise can read close to a 2 carat round from across a table. If apparent size matters more than the number on the certificate, choose an elongated shape and spend the difference on cut.

Which diamond shape sparkles the most?

Round, and it is not particularly close. The round brilliant is the only shape whose proportions were optimised specifically for light return, and every other brilliant shape is a compromise between that ideal and a different outline.

After round, the brilliant-faceted shapes (oval, pear, marquise, cushion, radiant, princess, heart) all sparkle well. The step cuts (emerald, asscher) are not competing on sparkle at all. They trade fire for those long clean flashes, and people who choose them do so precisely because they do not want a disco ball on their hand.

Cut grade beats shape here. A well-cut oval outperforms a poorly cut round, so if sparkle is the priority, buy the best cut grade you can before worrying about the outline.

Why shape changes what you pay

The price gap between shapes comes down to waste. A rough diamond crystal is roughly octahedral, and cutting a round from it discards a large share of the material. Fancy shapes use more of the crystal, so they cost less per carat for the same quality.

With mined stones that difference is significant. With lab-grown it still exists, but the whole scale shifts down: our shape collections start between $575 and $980, against the several thousand a comparable mined stone would command. That is why most of our customers use the saving to move up in size or clarity rather than pocket it.

One honest note. Shape does not affect resale much, because diamonds of any kind resell poorly relative to retail. Buy the shape you want to look at, not the one you think will hold value.

Pear HaloFrom $1,450 Marquise SolitaireFrom $1,087 Radiant PaveFrom $1,012 Asscher SolitaireFrom $1,087 Heart Split-ShankFrom $1,242

Which shape suits which hand and style?

These are tendencies, not rules. Try shapes on before you commit; photographs flatten everything.

• Shorter fingers: elongated shapes lengthen the hand. Oval, marquise, pear and emerald all work.
• Longer fingers: round, princess, asscher and cushion sit well without exaggerating length.
• Hands-on work: avoid points and sharp corners. Round, oval and cushion in a bezel or low setting survive daily life best.
• Classic taste: round or princess.
• Understated and modern: emerald or asscher.
• Vintage taste: cushion or asscher.
• Wants something different: marquise, pear or heart.

If you are matching a band to the ring later, shape matters there too. Elongated and pointed shapes need a contoured band to sit flush, which is worth knowing before you buy. Our wedding bands include curved designs cut to fit around a centre stone, and different wedding ring shapes pair better with some outlines than others.

Frequently asked questions