Diamond shape and diamond cut guide

Diamond engagement ring guide


In order to select your perfect diamond engagement ring, it can be helpful to understand the difference between diamond shape and diamond cut: two properties which are often confused.

The diamond shape refers to the outline shape of the diamond as you look at it from the top down. Round, Oval, Princess, Emerald, Cushion, Heart, Marquise, Asscher, Pear, Trapeze and Baguette are all shapes, and are often referred to as ‘fancy shapes’. When selecting the perfect shape for your diamond engagement ring several factors can guide you: The ring style you covet, your partner’s finger shape, or simply the design that captures your heart. 

The cut of a diamond is one of the 4Cs of diamond quality, along with Clarity, Colour and Carat. It does not refer to the diamond’s shape, but rather its proportions, symmetry and how well it has been cut and polished. In turn, these affect how much light the diamond emits, which will determine the degree to which it sparkles. These different types of light reflection are referred to as brilliance, fire (flashes of colour), and scintillation (how light reflects with movement). Only diamonds with a cut grade of Very Good or Excellent are eligible for De Beers Forevermark.


Featured ring: Pear Diamond Cut Engagement Ring

Diamond shapes

Round shape

This is the classic diamond shape for a diamond engagement ring. Round Brilliant is the name given to a diamond that is cut in such a way that light return, and therefore sparkle, are maximised.

Eligible for Forevermark

Cushion shape

The Cushion is square or rectangular with rounded corners. Timeless, and exquisitely proportioned, it works well in most setting types. Due to its larger facets it lends itself particularly well to vintage-style engagement rings.

Eligible for Forevermark

Princess shape

Princess shape diamonds have a square silhouette and a shallow crown. They offer optimum sparkle and are a popular choice for engagement ring settings that have a contemporary appearance.

Eligible for Forevermark

Emerald shape

These diamonds are cut into long and elegant rectangles and, more unusually, squares. Not only do they make fingers look slender, their graceful shape and shallow crown accentuate the diamond’s colour and clarity.

Eligible for Forevermark

Asscher shape

Also square in shape, Asscher diamonds are distinguished by their pointed culets and square cut corners. In contrast to the similar step cut square Emerald shape, an Asscher diamond’s steep facets enhance its brilliance.

Eligible for Forevermark

Marquise shape

This is a pointed oval shaped diamond whose unusual shape makes it a very desirable option in contemporary engagement rings. Its refined curves and elongated shape are also supremely flattering.

Eligible for Forevermark

Heart shape

When you promise your heart to your one true love, what could be a more iconic symbol of that romantic gesture than a Heart shape diamond?

Eligible for Forevermark

Oval shape

Because they can enjoy a variety of proportions, these versatile oblong diamonds flatter most finger shapes and are an elegant choice for many ring styles. Oval diamonds are a superb choice for a customer who likes the look of a classic round diamond, but wants something more contemporary.

Eligible for Forevermark

Pear shape

A striking blend of the Round and Marquise shape, Pear shape diamonds have a bewitching teardrop form. These diamonds are an outstanding choice to maximise brilliance and make for a more unusual diamond engagement ring.

Eligible for Forevermark

Radiant shape

This cuboid diamond combines the shape of an Emerald cut, with the sparkle of a Round Brilliant diamond. The triangular and kite shaped facets give the diamond intriguing depth and further enhance its natural beauty.

Eligible for Forevermark

Diamond cut scale


Diamonds in this category have the greatest sparkle. As light enters these diamonds it is reflected internally, from one mirror-like facet to another, and dispersed evenly. This perfectly balances the brilliant white light with intense flashes of fire (dispersion), giving the diamond its shine.

Eligible for Forevermark

Very Good

While the cut is not perfect, the majority of the light entering the diamond is still reflected through the top, or crown. This produces a level of very high white light often referred to as brilliance.

Eligible for Forevermark


Though it still reflects most of the light, a Good cut diamond appears slightly darker with a lack of contrast. Diamonds of this grade are not as brilliant as those of Excellent and Very Good grades, and so they are not eligible for the De Beers Forevermark inscription.


A Fair cut diamond, with facets cut only a few degrees out of alignment, can result in light leakage. This is where light exits through the bottom of the diamond instead of from the top, as is desired. This makes the diamonds slightly duller and therefore ineligible for De Beers Forevermark.

Diamond engagement ring checklist

Download our handy printable checklist to ensure you have everything you need before you visit your jewellers.

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Beyond the 4Cs

Throughout history, diamonds have dazzled and amazed. At De Beers Forevermark, we individually select diamonds against additional rigid criteria to ensure that only the most beautiful diamonds can become De Beers Forevermark.

Forever Guides

Sometimes a little help along the way is needed. From choosing the right ring size, to the perfect diamond engagement ring, or just simply how to care for your diamond; be inspired.