A Guide to Diamond Shapes

Choosing a diamond shape is one of the most personal decisions you’ll make when designing an engagement ring. While carat weight and clarity matter, it’s the shape that defines a diamond’s character. It’s what you notice first. It’s what gives a ring its presence.

There’s no universally “best” diamond shape, only the one that feels right on your hand, fits your lifestyle, and reflects your taste. At E.C.One, we guide clients through this decision every day, helping them try different shapes on and understand how each one behaves in the light.

This guide explores the most popular diamond shapes, what makes each distinctive, and how to begin narrowing down your choice.

What Is a Diamond Shape?

A diamond’s shape refers to its outline: round, oval, pear, square or elongated.

This is different from a diamond’s cut, which describes how well the stone’s facets interact with light. (We explore cut in more depth in our diamond education guides)

Shape influences:

> How large a diamond appears on the finger

> The style and feel of a ring

> How light reflects across the surface

> Which setting styles will suit it best

Round Brilliant

The round brilliant is the most classic and widely chosen diamond shape. With 58 carefully arranged facets, it is designed to maximise sparkle and light return.

Round diamonds feel timeless and balanced, a shape that has endured for generations. They work beautifully in simple solitaire settings, allowing the stone to speak for itself, but are equally strong in halo or trilogy designs.

At E.C.One, round brilliants are often chosen by those drawn to enduring elegance and simplicity.

E.C.One's Most Popular Round Diamond Engagement Rings: Genevieve, Hatty and Sophia.

Best for: Maximum sparkle, classic design lovers, timeless engagement rings.

Oval

Oval diamonds offer brilliance similar to a round, but with a softer, elongated silhouette. Because of their shape, they often appear larger than a round diamond of the same carat weight and can create the illusion of longer fingers.

They suit delicate bands, hidden halos, and modern claw settings particularly well.

E.C.One's Most Popular Oval Diamond Engagement Rings: Nancy, Olivia and Phoebe.

Best for: A balance of sparkle and individuality, flattering proportions.

Pear

The pear shape blends round and marquise influences, tapering to a single point. It’s distinctive and expressive, catching light in a way that feels dynamic.

Often associated with creativity and confidence, pear diamonds are chosen by those who want something slightly unexpected. They can be worn with the point facing up or down, each giving a different feel.

We particularly love pears in refined claw settings that protect the tip while keeping the silhouette elegant. 

E.C.One's Most Popular Pear Diamond Engagement Rings: Nancy and Josephine

Best for: Romantic, distinctive designs with a sense of movement.

Emerald Cut

Emerald cut diamonds are defined by long, linear step facets. Rather than sparkle intensely, they reflect light in broad, architectural flashes.

This shape is about clarity and proportion. It feels refined, structured and confident, understated rather than showy. Because the facets are open and transparent, stone quality is especially important.

Emerald cuts pair beautifully with clean bezel settings or minimal claws that emphasise their geometry.

E.C.One's Most Popular Emerald Cut Diamond Engagement Rings: Ava, Gracie and Audrey

Best for: Lovers of clean lines, Art Deco influence, understated strength.

Cushion

Cushion cut diamonds combine softened square or rectangular outlines with brilliant-style faceting. They have a romantic, slightly vintage character.

Their rounded corners give them warmth, while their facets offer a softer kind of sparkle. Cushion cuts often feel intimate and considered rather than bold.

E.C.One's Most Popular Cushion Cut Engagement Rings: Mila, Stella and Frame

Best for: Vintage-inspired designs, warmth and softness.

Marquise

Long and tapered at both ends, the marquise shape creates dramatic elongation on the finger. It has royal associations and a confident presence.

Because of its length, it can make a diamond appear larger than its carat weight suggests. It works particularly well in minimal settings that allow the silhouette to shine.

Best for: Statement rings, elongation, bold individuality.

Asscher

Square in outline with deeply stepped facets, the Asscher cut has a mesmerising hall-of-mirrors effect. It shares similarities with the emerald cut but feels more symmetrical and compact.

There’s a strong Art Deco sensibility to the Asscher — structured, balanced and quietly powerful.

E.C.One's Most Popular Asscher Diamond Engagement Rings: Genevieve, Juno and Evelyn

Best for: Architectural symmetry, vintage elegance.

Radiant

Radiant cut diamonds combine the clean outline of an emerald cut with the brilliance of a round. The result is a structured shape with lively sparkle.

They feel contemporary and energetic, offering brightness without losing geometry.

E.C.One's Most Popular Radiant Diamond Engagement Ring: Phoebe

Best for: Modern engagement rings with strong sparkle and defined edges.

How to Choose the Right Diamond Shape

When narrowing down your choice, it helps to consider a few practical and personal factors.

Lifestyle
If you lead an active lifestyle, certain shapes and settings may be more suitable. Protective settings such as bezels can help shield edges and points.

Hand shape
Elongated diamonds like oval, pear and marquise can lengthen the appearance of fingers. Round and cushion shapes create balance and softness.

Personality
Do you gravitate towards minimal, architectural design? Or something romantic and vintage-inspired? Your existing jewellery often offers clues.

Budget
Some shapes retain more of the original rough diamond during cutting, which can influence pricing. We’re always transparent about how these factors affect value.

Ultimately, seeing shapes on your hand makes the biggest difference. Photographs can guide you, but proportion and feeling are best experienced in person.

Craftsmanship Matters

At E.C.One, every engagement ring is crafted in our London workshop using recycled precious metals and responsibly sourced diamonds. The shape you choose is just the beginning - proportion, setting and finish all influence the final piece.

Whether you’re drawn to the timeless symmetry of a round brilliant or the architectural strength of an emerald cut, the craftsmanship behind the ring ensures it will be worn and loved for decades.

Still Unsure?

Choosing a diamond shape doesn’t have to feel overwhelming. Often, once you try a few on, one simply feels right.

If you’d like guidance, we’re always happy to talk through the options - whether you’re at the beginning of your search or refining a clear vision. Seeing the differences in person can make the decision far clearer than any guide ever could. Book a bespoke appointment here or see our opening times.