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A guide to diamond shapes

Loose diamonds of various shapes

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There are a large number of factors to consider when selecting a diamond engagement ring. For many, it starts with choosing the shape of the diamond. 

The shape is the first thing you see when looking at a diamond, so it's important that you choose wisely. With a range of diamond shapes to choose from, it can be challenging to know which to go for.

Understanding each shape and its pros and cons will enable you to make an informed decision when purchasing a diamond engagement ring. This article will identify the different shapes of diamonds available, the most popular ones and their advantages and disadvantages. 

What is a diamond shape? 

There are many different shapes of diamonds, but the most famous and by far the most popular is the round brilliant cut. In fact, all shapes other than the round are known as "fancy cuts", implying that they're a bit different to the norm. 

When choosing a diamond engagement ring, there is, of course, more to it than deciding on a shape of diamond that you like the look of. Some shapes are more expensive than others (in terms of cost per carat), some look bigger than others for the same carat weight, some sparkle more than others, and some show inclusions and colour more than others.

Knowing each shape inside-out is unnecessary, but learning the basics is an excellent start if you're looking at diamond engagement rings.

Below we've set out the nine most popular diamond cuts, each one having a unique shape.

Diamond shapes chart
Diamond shapes chart

Diamond shape vs. cut 

The diamond shape and cut are two terms that are often used interchangeably, and even the names of the diamond shapes include the word "cut", for example, princess cut, round cut, radiant cut, and so on.

However, strictly speaking, the diamond shape refers to the outline of the diamond when viewed from above (as shown in the chart above), whereas the diamond cut refers to either the cut grade of a round brilliant cut diamond or how a diamond is faceted. In modern diamond cutting, there are just two main ways of faceting diamonds, a brilliant cut, which is responsible for giving a diamond its fire through the refraction of light and stepped faceting. Most modern diamonds have brilliant faceting, with the emerald cut and Asscher cut being two notable exceptions.

Cut grades: round diamonds only

The Gemological Institute of America (GIA) developed the standards by which diamonds are graded for clarity, colour and cut. Only round brilliant cut diamonds are assessed for the quality of their cut, of which the GIA has five grades:

  • Excellent
  • Very good
  • Good
  • Fair
  • Poor

Some competing gemological authorities have developed slightly different grades. The International Gemological Institute (IGI) has, for example, created a top tier of excellent cut diamonds, which it grades as Ideal cut.

Round and fancy cut diamonds are graded for polish and symmetry using the five grades above, so when you see a round diamond referred to as triple EX, this means excellent cut, polish and symmetry. Since fancy cut diamonds are not given a cut grade, the highest they can achieve is double EX, meaning excellent polish and symmetry.

What are the most popular diamond shapes?

Every diamond shape is beautiful, but some shapes are more popular than others. Fashions change, but right now, the five most popular diamond shapes are:

  • Round
  • Oval
  • Emerald
  • Cushion
  • Princess

Below, we'll explore each of the five in further detail, including analysing their pros and cons.

Round cut diamonds

Round brilliant cut diamond

The most popular shape of a diamond is the round brilliant cut. This shape is so popular that it accounts for over half of the diamond engagement rings sold.

Round diamonds have a brilliance unparalleled by any other diamond shape. Their shape means they are uniquely positioned to be optimally faceted to maximise the reflection and refraction of light. In simpler terms, they are the sparkiest of the diamond shapes!

With a round cut diamond, there are many options for an engagement ring setting. Whether you go classic or modern, round diamonds are a worthy choice.   

A high level of brilliance, more so than other shapes Most expensive of diamond shapes (excluding rare shapes)
Classic and timeless in appearanceAs the most popular shape, not the best choice if you're looking for something a bit different
Suits every type of finger 
Suitable for all different settings
Flaws are well hidden

For more information, read our definitive guide to round brilliant cut diamonds.

Princess cut diamonds

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Princess cut diamonds evoke femininity and royalty and also deliver significant sparkle. Square in shape, it has a contemporary feel, perhaps not surprising given that it was only created in the 1960s.

Because of its large table, the princess cut diamond appears larger than some other shapes of the same carat weight. On top of this, you will actually get a bigger stone for your money than with many other shapes since the princess cut uses more of the rough stone than any other shape, meaning less goes to waste.

As the princess cut has sharp corners, it's more prone to chipping. However, certain settings will help protect the diamond.

A high level of brilliance, with optimal sparkle Sharp edges are more prone to chipping 
Looks great in both simple and detailed settings 
Inclusions are less visible 

For more information, read our definitive guide to princess cut diamonds.

Cushion cut diamonds 

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Square or rectangular, but with bowed sides and rounded off corners, cushion cut diamonds have been popular for centuries. 

It's a great and more affordable alternative to the round cut, as it shares similar characteristics while offering a more vintage feel. Its rounded edges also mean that this shape is less prone to chipping. While you should still be careful and look after your diamond, it's more durable than many other shapes. 

A cushion cut diamond is an ideal choice for those that love the appearance of antique engagement rings.

Similar to round-cut, but more affordableSmaller table than other fancy shapes
Round edges, therefore less prone to chipping Larger facets than some other shapes mean inclusions may be more visible
Shows off large amounts of fire
Vintage in appearance 

For more information, read our definitive guide to cushion cut diamonds.

Emerald cut diamonds

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Emerald cut diamonds are rectangular, but with the corners cut away (so strictly speaking octagonal). Unlike most diamond shapes, the emerald cut diamond has stepped rather than brilliant faceting. This means there is less refraction of light (sparkle) and more reflection of light (white flashes).

The stepped faceting, combined with the fact that the table (the top facet of the diamond) is noticeably larger than other shapes of the same carat weight, means that inclusions are more visible in emerald cuts than they are in other diamond shapes of the same clarity grade.

Likewise, emerald cuts show colour more readily than other diamond shapes, so you may wish to select a stone of higher colour and clarity if you go with an emerald cut. However, this is largely offset by the fact that the cost per carat of emerald cut diamonds is often less than that of other shapes.

The emerald cut diamond was extremely popular in the Art Deco period, so it is an excellent choice for those looking to create an Art Deco-inspired engagement ring.

Distinctive designClarity and colour show more than most other shapes 
Looks larger than most other shapes of the same carat weight
Elongates the finger
More affordable than other shapes 

For more information, read our buyers' guide to emerald cut diamonds.

Oval cut diamonds

Oval cut diamonds are the perfect choice for those who love the round cut's elegance but are looking for something a little more unusual. Ovals are also generally more affordable than round diamonds with similar grades.

An oval diamond appears larger (when viewed from above) than a round diamond of the same carat weight due to being cut with a large "spread". In addition, their elongated shape means oval diamonds are very flattering to the finger.

Oval diamonds are one of the diamond shapes that exhibit a phenomenon known as the bow-tie effect. This is a pattern of light and dark with the diamond, which can give the impression of a dark stripe through the centre of the stone. It is difficult to find ovals without any bow tie effect, but ovals that have been well cut should not show a strong bow-tie effect.

High levels of brillianceThe bow tie effect can cast a shadow across the table of your diamond
Round edges mean it is less prone to chipping
Flattering to the finger 
Look large for their carat weight
Vert versatile, suiting many types of styles and settings

For more information, read our buyers' guide to oval cut diamonds.

Guides to other diamond shapes

If you're looking for a slightly for a diamond shape that is a little bit more unusual, we've also written a guide to radiant cut diamonds, a guide to pear cut diamonds, a guide to marquise cut diamonds, and a guide to Asscher cut diamonds.

Which diamond shape is the rarest?

It takes a highly skilled diamond cutter to cut a diamond to high quality. However, for the rarest of shapes, only very few are skilled enough to be able to cut them. Four of the rarest diamond shapes are:

  • Ashoka cut - a rectangular variant of the cushion cut with 62 facets.
  • Royal Asscher cut - similar to the Asscher, this shape has an extra 16 facets, perfect symmetry and a higher crown.
  • Lily cut - perhaps the most unusual of all diamond shapes, the lily cut resembles a flower.  
  • Eighty-eight cut - octagonal and with eighty-eight facets; because of how this diamond has been cut, it sparkles intensely even under low lighting levels.

How to choose a diamond shape

If you've not been given any hints, think about your partner's style preferences. Do they tend to favour traditional or modern designs? Do they prefer classic styles, or do they prefer something more unusual? If you are struggling to decide for yourself, you might try asking their closest friends and family.

But if you're still unsure of your significant other's preference, unless you know they would prefer something a little bit unusual, you probably can't go far wrong choosing the round brilliant cut. There are good reasons why it is by far the most popular diamond shape. Not only does it lend itself perfectly to a wide array of jewellery designs, but it sparkles like no other!

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Your journey to your dream diamond engagement ring is likely to begin with the shape. Each shape is unique and beautiful in its own way, with its own pros and cons. 

Our diamond and jewellery experts are more than happy to answer any questions about diamond shapes and help you choose the ideal shape for your diamond engagement ring.

Tim Ingle
Together with David Rhode, Tim created Ingle & Rhode to offer a better alternative to the traditional luxury brands. Since 2007, we’ve provided our customers with genuinely ethical engagement rings, wedding rings and fine jewellery – free from conflict diamonds, dirty gold and child labour. With more than 16 years experience in the jewellery industry, Tim has deep expertise in diamonds, gemstones and jewellery design and manufacturing.