A diamond's shape is its outline, and it is the first thing most people notice and the most personal choice you make. This guide runs through the ten shapes you will actually come across, the character of each, which ones look largest for their weight, and, importantly, how the colour and clarity you should look for changes from one shape to the next.
A diamond's shape is its outline seen from above, such as round, oval, emerald or pear. Round is the most popular and the most brilliant, while elongated shapes like oval, pear and marquise look larger for their weight. Shape is mostly a matter of taste, but it also changes what to look for: some shapes hide colour and inclusions well, while others show them and ask for a higher grade.
What is a diamond shape?
A diamond's shape is its geometric outline when you look down at it from above: round, oval, square, rectangular, a teardrop, and so on. It is the silhouette of the stone, and it is chosen purely on taste and how it suits the wearer or the piece. The ten shapes worth knowing are round, oval, princess, cushion, emerald, pear, marquise, radiant, Asscher and heart. Round is by far the most popular, accounting for most diamonds sold, and everything else is grouped together as a fancy shape.
Shape is not the same as cut
Shape and cut sound alike but they are two different things, and the difference is worth holding onto. Shape is the outline, round or oval or pear. Cut is the quality of the faceting within that outline, how well the stone has been proportioned and polished to return light. Two oval diamonds can share the same shape yet look completely different, one lively and bright, the other dull, because one is cut well and the other is not. Shape is a matter of taste, while cut is a matter of quality, and cut is the part that most decides how a diamond sparkles. Our guide to the 4Cs explains cut in full.
Brilliant cuts and step cuts, and why it changes what to look for
Nearly every shape is faceted in one of two ways, and this is the single most useful thing to understand before choosing, because it decides how forgiving a shape is on colour and clarity.
Brilliant-cut shapes have many small, angled facets, usually around 57 or 58, arranged to scatter light in every direction. That scattering is what creates sparkle, and it has a helpful side effect: it breaks up the view into the stone, so small inclusions and a faint tint of colour tend to disappear into the sparkle. Round, oval, cushion, pear, marquise, radiant, princess and heart are all brilliant cuts.
A timeless classic, the Emerald cut is a step cut named after the gemstone for which it was created.
Step-cut shapes, mainly the emerald and the Asscher, are faceted differently. They have long, straight facets running parallel to the edges, like steps, which gives a clear "hall of mirrors" look with flashes of light rather than fireworks. Because you are looking straight into an open, glassy stone, there is nowhere for a flaw or a tint to hide, so step cuts show both inclusions and colour more readily. The practical result is simple: a step cut asks for a higher clarity and a higher colour grade than a brilliant shape of the same size, while a brilliant shape lets you spend a little less on those and still look eye clean and white.
The diamond shapes, and what to consider for each
Here is each shape, its character, and the colour and clarity worth looking for. The grades below are a starting point, not a rule, and any stone is best judged with your own eyes or from clear 360 degree imagery.
Round brilliant. The classic and the most popular by far, engineered over a century to return the most light of any shape, so it is the brightest and the most versatile. It is also the most forgiving: its sparkle hides colour and inclusions better than any other shape, so a near colourless grade and an eye clean stone in the VS to SI range will look beautiful. It carries the most light for its weight, which is part of why it costs more per carat than fancy shapes.
Oval. A brilliant cut with the sparkle of a round but stretched, so it looks larger for its weight and flatters the finger. Being elongated, its wider surface shows colour a touch more than a round, so it is worth leaning slightly whiter, around G or better. Ovals can also show a "bowtie", a darker band across the centre caused by the cut rather than the stone, so check that it is faint before you choose.
Princess. A square brilliant with crisp corners and lively sparkle, a modern classic. Its faceting hides inclusions well, so you can sit a little lower on clarity, but it holds colour in the corners, so lean slightly whiter if that matters to you. The sharp corners are its one vulnerable point and can chip, so a setting that protects them is worth having.
Cushion. A softened square or rectangle with rounded corners and a warm, romantic sparkle. It is a brilliant cut and hides inclusions well, so an eye clean SI can work nicely, while its slightly larger facets can show a little colour, so near colourless is a safe choice.
Emerald. A step cut, rectangular with cut corners, elegant and understated with long flashes of light rather than sparkle. Because it is open and glassy, it shows inclusions clearly, so a higher clarity of VS2 or better is worth it, and it shows colour, so lean whiter too. In return it has a wonderfully clean, architectural look, and it tends to cost less per carat than a round.
Asscher. A square version of the emerald, another step cut, with a striking "hall of mirrors" depth. The same advice applies: choose a higher clarity, around VS2 or better, and a whiter colour grade, since there is nowhere for a flaw or a tint to hide.
Pear. A brilliant-cut teardrop, one round end and one point, graceful and elongated so it looks large for its weight. Like the oval it can show a bowtie, and it can hold a hint of colour at the pointed tip, so viewing it in person helps and a slightly whiter grade is safer. The point is delicate, so it is usually protected by the setting.
Marquise. A long brilliant cut with two pointed ends, the shape that looks largest of all for its carat weight, and slimming on the finger. It can show a bowtie and a little colour at the tips, so lean whiter and check the symmetry, since any unevenness shows in such a long outline. The tips need protecting like the pear's.
Radiant. A rectangular or square shape with full brilliant faceting, so it sparkles like a round but with clean straight sides, a lively cross between an emerald outline and a brilliant interior. That faceting hides inclusions and colour well, making it one of the more forgiving fancy shapes, so an eye clean SI in a near colourless grade holds up nicely.
Heart. A brilliant cut, romantic and unmistakable, essentially a pear with a cleft at the top. It needs good symmetry to read cleanly, and it can hold a little colour at the point, so lean slightly whiter. It suits pendants especially, where the shape is shown off at its best.
| Shape | Character, and what to consider | |
|---|---|---|
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Round | Brightest and most popular. Hides colour and inclusions best, so the most forgiving grades. |
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Oval | Round's sparkle, looks larger. Lean slightly whiter, check for a bowtie. |
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Princess | Crisp square sparkle. Hides inclusions, holds colour in the corners, protect the corners. |
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Cushion | Soft, romantic sparkle. Hides inclusions well, near colourless is safe. |
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Emerald | Elegant step cut. Shows inclusions and colour, so choose VS2 or better and whiter. |
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Asscher | Square step cut, hall of mirrors. Same as emerald: higher clarity and colour. |
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Pear | Elongated teardrop, looks large. Lean whiter, check the bowtie and the tip. |
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Marquise | Looks largest for its weight. Lean whiter, check symmetry, protect the tips. |
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Radiant | Brilliant sparkle, straight sides. Forgiving on colour and clarity. |
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Heart | Romantic, needs good symmetry. Lean slightly whiter, lovely as a pendant. |
Which diamond shape looks the biggest?
Elongated shapes look the largest for their carat weight, because they spread more of the diamond across the top where you see it. Marquise looks biggest of all, followed closely by oval and pear, which appear roughly 10 to 25 percent larger face-up than a round of the same weight. Round tends to look the smallest for its weight, since more of its carat sits in depth below the surface to feed the sparkle.
If size for your budget is the priority, an elongated shape like oval, pear or marquise gives you the most visible diamond per carat, and flatters the finger too. If maximum sparkle is the priority, round is unmatched. Remember that carat is weight, not size, so how a shape spreads that weight is what changes the look. Our guide to carat weight and size shows this with a size chart.
How to choose a diamond shape
Start with the shape you are simply drawn to, because shape is the one part of a diamond that is purely personal and there is no wrong answer. From there, let a few practical points refine it. If you love a step cut like the emerald or Asscher, put your budget into a higher clarity and colour so the open facets stay clean and white. If you want the most size, lean to an elongated brilliant shape. If you want the most sparkle and the most forgiving grades, round is the safe and brilliant choice. And if a shape has points or corners, like the marquise, pear, heart or princess, a setting that protects them keeps it safe for daily wear.
Whatever shape you choose, the cut quality within it still decides how it looks, so it is worth reading how to choose a diamond next, and the wider guide to diamonds ties shape together with the rest. You will find a range of shapes across our diamond studs and diamond pendants, where the shape is shown off simply and worn every day.
