Choosing an engagement ring starts with one decision that affects everything else, the diamond’s shape. Understanding diamond shapes and their names gives you a clear advantage when you’re comparing options, because each shape interacts with light differently, suits different hand types, and carries its own visual character. Getting this right matters, it’s the centrepiece of a ring your partner will wear every single day.

At A Star Diamonds, our goldsmiths and gemologists in Hatton Garden help couples with this exact decision every week. We design bespoke engagement rings around each client’s chosen stone, so we see first-hand how much the shape influences the final piece. Whether you visit our workshop or start your research here, a solid understanding of your options makes the whole process smoother and more enjoyable.

This guide covers nine of the most popular diamond shapes for engagement rings, from the classic round brilliant to the bold marquise. For each one, we’ll explain what makes it distinct, who it tends to suit, and how it looks once set in a ring.

1. Round brilliant

The round brilliant is the most popular diamond shape in the world, and for good reason. Its symmetrical circular outline and 58-facet structure make it the benchmark that every other shape is compared against. If you’re starting your search without a strong preference, the round brilliant is almost certainly the shape you picture when you think of an engagement ring diamond.

How to recognise it at a glance

A round brilliant is exactly what its name suggests: a perfectly circular stone viewed from above, with a pointed culet at the base when viewed from the side. No other shape mimics this silhouette. The clean, uninterrupted curve around the girdle is immediately recognisable, and there are no corners, points, or flat edges to break the outline.

Sparkle style and face-up size

The round brilliant produces the highest level of brilliance of any diamond shape, thanks to decades of optical research refining its exact proportions. Light enters the stone, bounces between the angled facets, and exits back through the top as bright white flashes and coloured fire. The trade-off is that round diamonds appear smaller face-up per carat than elongated shapes like oval or pear, because the circular outline does not stretch across the finger.

A well-cut round brilliant reflects more light than any other shape, which is why cut quality matters more for this shape than for almost any other.

Best settings for round diamonds

Round brilliant diamonds suit virtually every ring setting style, from a classic four-prong solitaire to a full pavé or halo band. A four-prong or six-prong claw setting keeps the stone elevated and draws light in from all angles, maximising sparkle. A bezel setting wraps a metal rim around the girdle for a cleaner, more contemporary look while offering extra protection for everyday wear.

Buying tips for cut, colour, and clarity

Cut is the single most important factor for a round brilliant. Prioritise a GIA Excellent or Very Good cut grade and you will see the difference straight away. For colour, stones in the G to H range face up white in most settings, and clarity at VS2 or SI1 is typically eye-clean, giving you strong visual quality without paying a premium for characteristics invisible to the naked eye.

2. Oval

The oval is one of the most-recognised diamond shapes and their names sits naturally in the brilliant-cut family, placing it just behind the round in popularity. Its elongated outline flatters the finger and delivers strong sparkle at a competitive price per carat compared to round brilliants of the same weight.

How to recognise it at a glance

An oval has a smooth, elliptical outline with no corners or points, symmetrical on both its long and short axes. It is immediately distinct from pear or marquise shapes, both of which taper to a point at one or both ends.

Sparkle style and face-up size

The oval follows a brilliant-cut facet pattern, producing bright white flashes very similar to a round. Its elongated shape means it reads noticeably larger on the finger per carat than a round brilliant, making it strong value for buyers who want maximum visual size.

An oval can appear up to 10% larger face-up than a round diamond of the same carat weight.

Length-to-width ratio guide

Target a ratio between 1.35 and 1.50 for the most balanced look. Below 1.30 the stone appears nearly circular, and above 1.55 it starts to look narrow and stretched across the finger.

Common issues to check, including bow-tie

Most oval diamonds carry a bow-tie effect, a dark shadow running across the stone’s centre. A faint one is normal, but a heavy bow-tie kills brilliance. Always view the stone in person or request a video before committing to a purchase.

Best settings and prong protection

A four or six-prong claw setting is the standard choice for ovals, keeping the stone elevated and open to light. There are no sharp corners to chip, so ovals suit everyday wear well, though a bezel setting provides the most complete girdle protection if that is a priority for you.

3. Cushion

The cushion cut has been around for nearly two centuries, and it remains one of the most beloved diamond shapes and their names in the brilliant-cut family. Its softened square or rectangular outline with rounded corners gives it a warm, vintage character that suits a wide range of engagement ring styles.

How to recognise it at a glance

A cushion has a square or rectangular body with noticeably rounded corners, resembling a pillow. The girdle outline is fully curved, not angular, which sets it apart immediately from a princess cut when you view the stone face-up.

Cushion facet styles and sparkle look

Cushion cuts come in two main facet patterns. Cushion brilliant cuts produce broad, chunky flashes of light, while cushion modified brilliant cuts produce a finer, glittery sparkle pattern sometimes called crushed-ice. Neither is superior; it comes down to personal preference.

Cushion modified brilliants appear icier under direct light, while cushion brilliants show larger, warmer flashes.

Face-up size and value for money

Cushions carry more weight in the depth of the stone rather than the spread, which means they face up slightly smaller per carat than ovals or pears. You typically get better value per carat compared to a round brilliant of equivalent quality.

Best settings for cushion diamonds

A four-prong claw setting works well, with prongs placed at each rounded corner to hold the stone securely. Halo and pavé band settings both complement the cushion’s soft outline naturally and add perceived size.

What to check on symmetry and outline

Check that both axes are symmetrical and the corners curve evenly. An uneven outline looks noticeably off-centre once the stone is set, so always request a top-down image before you buy.

4. Princess

The princess cut is the most popular square diamond shape in the brilliant-cut family, sitting second only to the round in overall engagement ring sales. Its clean, geometric profile appeals to buyers who want a modern look without giving up the high sparkle output that brilliant cuts deliver.

How to recognise it at a glance

A princess cut has a perfectly square or near-square outline with four sharp, uncut corners when viewed face-up. Viewed from the side, the stone tapers to a near-point at the base, creating a distinctive inverted pyramid profile that no other shape shares.

Sparkle style and face-up size

The princess produces brilliant-cut sparkle with a high-contrast, firework-like light return that competes closely with the round. Because more of the carat weight sits in the spread rather than the depth, the princess faces up noticeably larger per carat than a round brilliant of the same weight.

A princess cut can show roughly 15 to 20% more face-up area than a round diamond of identical carat weight.

Durability notes for sharp corners

The four unprotected corners are the princess cut’s biggest vulnerability. Each sharp tip concentrates impact stress, making chipping a real risk during everyday wear, particularly for anyone with an active lifestyle or a physical job.

Best settings and corner protection

A four-prong setting with V-shaped prongs placed at each corner is the standard and most practical choice. The V-prong wraps directly around each tip, shielding the most fragile points from knocks and reducing the risk of damage significantly.

What to check on depth and light return

Avoid any princess cut with a table percentage above 76% or total depth below 65%, as both signal proportions that will weaken light return. Always ask for a GIA or IGI grading report so you can verify the exact measurements before you finalise your purchase.

5. Emerald

The emerald cut stands apart from every other entry in this guide to diamond shapes and their names because it belongs to the step-cut family rather than the brilliant-cut family. Where brilliant cuts scatter light in every direction, the emerald cut uses long, parallel facets arranged in steps to produce a slower, more deliberate optical display.

How to recognise it at a glance

An emerald cut has a rectangular outline with four bevelled corners, giving it an octagonal silhouette when viewed face-up. The large flat table and open facets make the stone’s interior immediately visible, unlike any brilliant-cut shape.

Step-cut sparkle and the hall-of-mirrors look

Rather than delivering flashes of brilliance, an emerald cut produces broad, glassy reflections that shift as the stone moves. This effect is known as the hall-of-mirrors look, created by the long step facets reflecting each other internally.

The hall-of-mirrors effect rewards well-proportioned stones cut from high-clarity material more than any other diamond shape.

Colour and clarity tips for step cuts

The open facets leave colour and inclusions more exposed than a brilliant cut would. Target G colour or above and VS2 clarity minimum to keep the stone looking clean and bright to the naked eye.

Length-to-width ratio guide

Target a ratio between 1.30 and 1.50 for the most classic emerald-cut look. Below 1.25 the stone reads more like a square Asscher cut, and above 1.55 it appears noticeably long and narrow on the finger.

Best settings for clean lines and protection

A four-prong or bezel setting works best, keeping the clean geometric outline uncluttered. The bevelled corners reduce chipping risk compared to a princess cut, but a bezel provides maximum protection for active wearers.

6. Radiant

The radiant cut combines the step-cut rectangular outline of an emerald cut with a brilliant-cut facet pattern, which places it in a unique position among diamond shapes and their names. This makes it a versatile option for buyers who want a rectangular or square stone without giving up sparkle output.

How to recognise it at a glance

A radiant has a rectangular or square outline with four cropped corners, similar to an emerald cut at first glance. The key difference is the complex brilliant facets visible beneath the table, which produce a busy, glittery surface rather than the clean step reflections of an emerald cut.

Sparkle style and the crushed-ice look

The radiant’s facet structure creates a fine, scattered sparkle pattern often described as crushed ice. This is distinct from the broad, chunky flashes of a cushion brilliant, and the difference is obvious as soon as you view both shapes side by side.

The crushed-ice sparkle style hides inclusions and colour tints more effectively than most other shapes, making radiants particularly forgiving to grade.

Face-up size and value for money

Radiants carry moderate depth, which means they face up slightly smaller per carat than an oval. You typically pay less per carat than an equivalent round brilliant of the same quality grade, making the radiant strong value for money.

Colour and clarity flexibility

Because the crushed-ice facet pattern breaks up light so aggressively, colour and inclusions are harder to detect face-up. Stones in the H to I colour range and SI1 clarity often look clean and bright in real-world lighting.

Best settings for cropped corners

The cropped corners reduce chipping risk significantly compared to a princess cut. A four-prong setting with prongs placed at each corner works well, as does a bezel for a more protective, contemporary finish.

7. Pear

The pear cut blends a rounded base with a tapered point, creating one of the most distinctive entries in the catalogue of diamond shapes and their names. Its asymmetrical teardrop silhouette gives it a romantic, feminine character that many buyers find instantly compelling.

How to recognise it at a glance

A pear has a fully rounded base that narrows gradually to a single sharp point at the opposite end. No other shape combines a curved end with a single tapering tip, making the pear immediately recognisable face-up even at a quick glance.

Sparkle style and face-up size

The pear follows a brilliant-cut facet pattern, producing strong white flashes and fire across the stone’s surface. Its elongated outline means it faces up noticeably larger per carat than a round brilliant of the same weight, giving you strong visual value.

A pear worn with the point toward the fingertip elongates the appearance of shorter fingers more effectively than almost any other shape.

Length-to-width ratio guide

The length-to-width ratio directly shapes how a pear reads on the finger, and it is worth checking before you finalise any purchase.

Common issues to check, including bow-tie

Most pear diamonds carry a bow-tie shadow across the widest section of the stone. A faint one is acceptable, but a heavy bow-tie reduces brilliance noticeably, so always view the stone on video or in person before you commit.

Best settings to protect the tip

The pointed tip is the most vulnerable part of a pear and the area most likely to chip on impact. A V-prong placed at the tip is the standard solution, wrapping the sharp end in metal to protect it from knocks during everyday wear.

8. Marquise

The marquise is one of the most recognisable entries in the catalogue of diamond shapes and their names, combining an elongated body with two sharp points at each end. Its dramatic silhouette makes an immediate statement on the finger, and it suits buyers who want something bold and unconventional without straying too far from a classic brilliant cut.

How to recognise it at a glance

A marquise has a football-shaped outline with two sharp, symmetrical points at opposite ends and a gently curved body connecting them. No other shape combines a fully elongated form with a tip at both ends, making it instantly recognisable even at a quick glance.

Face-up size and finger-elongating effect

The marquise delivers one of the largest face-up areas per carat of any diamond shape available. Worn lengthways along the finger, it creates a strong visual elongation that makes fingers appear noticeably longer and slimmer, a quality many buyers actively seek out.

A marquise can show up to 15% more face-up spread than a round brilliant of the same carat weight.

Length-to-width ratio guide

Target a ratio between 1.75 and 2.15 for the most balanced marquise proportion. Below 1.70, the stone appears wide and stubby, while above 2.20 it looks overly narrow and structurally fragile across the setting.

Common issues to check, including bow-tie

Most marquise diamonds carry a bow-tie shadow across the centre of the stone. A subtle one is acceptable, but a heavy bow-tie noticeably reduces brilliance. Always request a video or view the stone in person before committing to a purchase.

Best settings and V-prong protection

Both pointed tips are the most vulnerable areas on a marquise diamond. A setting with V-prongs placed at each tip is essential for shielding these fragile ends from chipping during everyday wear.

9. Heart

The heart is the most emotionally loaded entry in this guide to diamond shapes and their names. Its romantic silhouette makes it an obvious choice for couples who want their ring to carry visible meaning, but the shape demands careful assessment before you commit to a purchase.

How to recognise it at a glance

A heart has a rounded, symmetrical body that splits into two curved lobes at the top and tapers to a single sharp point at the base. The central cleft dividing the two lobes is what separates a heart from a pear at first glance.

When the heart shape looks its best by carat size

The heart’s defining outline only becomes legible at larger carat sizes. Stones below 0.70 carats tend to lose their clear heart silhouette in most settings, making the shape harder to read face-up.

Choose a heart diamond of at least 0.80 carats to ensure the shape reads cleanly once it is set in a ring.

Symmetry checkpoints: lobes, cleft, and point

Check three specific areas before you buy a heart diamond, as any asymmetry reads immediately once the stone is set:

• Both lobes must mirror each other in size and curve
• The cleft must sit centrally and reach a well-defined depth
• The point must align directly with the central axis of the stone

Sparkle style and face-up size

The heart follows a modified brilliant-cut facet pattern, delivering strong light return across the stone’s surface. Its spread across the finger means it faces up generously for its carat weight.

Best settings to keep the heart outline clear

A three-prong or five-prong setting works best, with a V-prong protecting the point and individual prongs cradling each lobe to keep the full outline visible and unobscured by metalwork.

Next steps

You now have a working knowledge of diamond shapes and their names, from the high-sparkle round brilliant to the romantic heart. Each shape has its own strengths, trade-offs, and ideal settings, and the right choice depends on your partner’s hand, lifestyle, and personal style rather than any single rule about what looks best.

Use what you’ve read here to narrow your list to two or three shapes before you start comparing individual stones. Knowing what you’re looking for makes every conversation with a jeweller faster and more productive, and it puts you in a far stronger position when you’re evaluating real options side by side.

If you’re ready to take the next step, the team at A Star Diamonds in Hatton Garden can help you find the right stone and design a bespoke ring around it. Book a consultation with A Star Diamonds to start building your perfect engagement ring.