Diamond Education
Diamond Shapes
All ten shapes compared, how each one sparkles, what it costs next to a round, which look largest per carat, and what to check before you buy.
By 25karats · Updated 2026 · 8 minute read
Shape is a diamond’s outline seen from above, and it is the decision that changes the look of a ring more than any other. It is also the one that quietly moves the price by 40%.
Round brilliants dominate, but fancy shapes have been steadily taking share, and for good reason: they cost less per carat and several of them look considerably larger on the finger. Here is the whole set, with the trade-offs stated plainly.
Two things to know before the shapes
| Shape | Price vs. round | Face-up size per carat | Light character |
|---|---|---|---|
| Round | Highest | Average | Maximum brilliance |
| Oval | Lower | Large | Brilliant |
| Marquise | Much lower | Largest | Brilliant |
| Pear | Lower | Large | Brilliant |
| Emerald | Much lower | Large | Step-cut flashes |
| Asscher | Much lower | Small | Step-cut flashes |
| Princess | Lower | Small | Brilliant |
| Cushion | Lower | Average | Brilliant, high fire |
| Radiant | Lower | Average | Brilliant |
| Heart | Lower | Average | Brilliant |
The practical upshot: an oval or marquise gives you visible size for your money, an emerald or asscher gives you elegance for your money, and a round gives you sparkle at a premium.
The ten shapes
Round Brilliant
Fifty-seven or fifty-eight facets engineered over a century to return the maximum amount of light. It is the most brilliant shape, the most forgiving of a lower color or clarity grade, and the most expensive per carat.
Watch for: Nothing structural to worry about, just buy the best cut grade you can. This is the one shape where cut is graded rigorously by every laboratory.
Ideal length-to-width: 1.00 – 1.01
Oval
An elongated round brilliant. It keeps most of round's sparkle, looks noticeably larger than its carat weight, and elongates the finger. The fastest-growing choice for engagement rings.
Watch for: The bow-tie: a dark band across the center caused by uneven light return. Every oval has one to some degree; you want it faint enough not to notice.
Ideal length-to-width: 1.30 – 1.50
Princess
A square brilliant with sharp, uncut corners. Strong sparkle, a distinctly modern outline, and typically well below round in price for the same weight.
Watch for: Those pointed corners are the most vulnerable part of any square cut. Insist on a setting with protective V-prongs over each corner.
Ideal length-to-width: 1.00 – 1.05
Cushion
A softened square with rounded corners, like a pillow. Larger facets give it more fire (coloured flashes) than round, with a warmer, more antique character.
Watch for: Cushion covers a wide range of facet patterns. 'Crushed ice' looks glittery and busy; 'chunky' shows bigger flashes. They look very different, so view before buying.
Ideal length-to-width: 1.00 – 1.09 square, 1.15 – 1.25 rectangular
Emerald
A step cut: broad, flat facets in parallel rows producing long flashes rather than sparkle, and a hall-of-mirrors depth. Architectural, understated, and excellent value per carat.
Watch for: Those open facets hide nothing. Buy a higher clarity than you would for a brilliant cut, VS2 or better, and expect any warmth of color to be visible.
Ideal length-to-width: 1.30 – 1.60
Pear
A teardrop, round at one end and pointed at the other. Elongating on the finger, distinctive, and versatile enough for rings and pendants alike.
Watch for: Check symmetry down the long axis: an off-centre point is obvious once seen. The point needs a protective prong, and pears can show a bow-tie.
Ideal length-to-width: 1.45 – 1.75
Marquise
A long boat shape with points at both ends. It carries its weight across the widest possible surface, so it looks larger face-up than any other shape at the same carat.
Watch for: Two points to protect rather than one, and the most pronounced bow-tie risk of any shape. Symmetry between the two halves matters a great deal.
Ideal length-to-width: 1.75 – 2.25
Radiant
An emerald outline with brilliant faceting inside: cut corners and step-cut sides, but the sparkle of a round. It bridges the gap between the two families.
Watch for: The brilliant faceting hides inclusions well, so you can drop a clarity grade, but it also concentrates color, so go a grade higher on color than you would for an emerald cut.
Ideal length-to-width: 1.00 – 1.05 square, 1.30 – 1.50 rectangular
Asscher
A square step cut with cut corners, first cut in 1902 and revived with the Art Deco taste it belongs to. Its concentric facets produce a distinctive windmill pattern.
Watch for: Like the emerald cut, it shows everything. Prioritise clarity and color, and look straight down into the stone to check the windmill is even.
Ideal length-to-width: 1.00 – 1.05
Heart
A pear with a cleft, and the most difficult shape to cut well. Unambiguously romantic and genuinely uncommon, which is part of the appeal.
Watch for: Symmetry is everything: the two lobes must match and the cleft must be distinct. Below about 0.50 carat the shape becomes hard to read on the finger.
Ideal length-to-width: 0.90 – 1.10
Length-to-width ratio, and why it matters
For any shape that is not round, the length-to-width ratio decides the outline, whether an oval reads as a stretched circle or a slim ellipse. It is printed on every grading report, and it is entirely a matter of taste, so the ranges below are conventions rather than rules.
| Shape | Common ratio | Effect of going higher |
|---|---|---|
| Oval | 1.30 – 1.50 | Slimmer and more elongating; bow-tie tends to worsen |
| Emerald | 1.30 – 1.60 | More elegant and linear; below 1.30 approaches a square |
| Radiant | 1.30 – 1.50 | Rectangular rather than square; both are popular |
| Pear | 1.45 – 1.75 | More dramatic; the point becomes more fragile |
| Marquise | 1.75 – 2.25 | Longer and narrower; bow-tie becomes more likely |
| Cushion | 1.00 – 1.25 | 1.00 is a square cushion, 1.15+ reads clearly rectangular |
| Princess, asscher, heart | ~1.00 | These are square or symmetrical by definition |
There is no wrong answer here. A 1.60 oval is not worse than a 1.35. It is simply a different look, and it is worth deciding which you prefer before you start comparing stones.
Shape changes what you should buy
The 4Cs are not applied identically across shapes. Getting this right is where the money is.
Step cuts need higher clarity and color
Emerald and asscher cuts have large, open, mirror-like facets that conceal nothing. Buy VS2 or better and go a grade higher on color than you otherwise would, both will be visible. See our clarity guide.
Brilliant cuts hide inclusions
Round, cushion, radiant, and princess scatter light in every direction, which masks small inclusions. SI1 often looks eye-clean, and that is where the value is.
Elongated shapes concentrate color at the tips
Pear and marquise gather body color at their points, so warmth shows there first. Add a grade of color, or set them in yellow gold where it reads as intentional. See our color guide.
Only round is graded for cut by every laboratory
Fancy shapes rarely carry a formal cut grade, so you cannot lean on the report. Judge symmetry, look for the bow-tie, and view the stone or a video before committing. See our cut guide.
Points and corners need protecting
Marquise, pear, and heart shapes have points; princess cuts have sharp corners. These are the parts that chip. Use V-prongs or a bezel, particularly on a hand that works.
Choosing your shape
If you want maximum sparkle
Round brilliant, and accept the premium. Nothing else returns light as completely.
If you want the biggest look
Oval or marquise. Both spread their weight across a wide face and elongate the finger.
If you want understated elegance
Emerald or asscher. Step cuts trade sparkle for clean architectural flashes, and cost far less per carat.
If you want something uncommon
Pear or heart. Both are distinctive, and both reward careful attention to symmetry.
If the hand is hard on jewelry
Round, oval, or cushion in a bezel. No points, no sharp corners, nothing to catch or chip.
If the budget is fixed
Change the shape before you drop carat weight. Moving from round to emerald or marquise buys visible size at the same price.
Frequently asked questions
Which diamond shape is the cheapest?
Every shape is cheaper than round. Emerald, marquise, and asscher are typically the best value: often 20–40% below round for the same carat and grades, because they waste less rough in cutting and demand is lower.
Which shape looks the biggest?
Marquise, then pear and oval. Elongated shapes spread their weight across a wider face-up surface. Round, princess, and asscher carry more weight in depth, so they look smaller at the same carat.
Which shape sparkles the most?
Round brilliant, which was engineered for exactly that. Emerald and asscher are step cuts and produce long flashes and depth rather than sparkle: a different effect, not a lesser one.
What is a bow-tie?
A dark band across the center of an elongated diamond where the facets fail to return light. Oval, marquise, and pear all have one to some degree. No report grades it, so you have to look at the stone or a video of it.
Is shape the same thing as cut?
No, though the words get used interchangeably. Shape is the outline: round, oval, pear. Cut is how well the stone’s proportions and facets were executed, and it is what determines whether it sparkles. A beautifully shaped diamond that is poorly cut still looks dull.
Does diamond shape affect what clarity and color I need?
Yes, considerably. Step cuts like emerald and asscher have large open facets that reveal inclusions and color, so buy higher grades. Brilliant cuts like round, cushion, and radiant scatter light and hide inclusions, so you can go lower on clarity. Elongated shapes concentrate color at their tips, so add a grade of color for pear and marquise.
Compare shapes side by side
Browse IGI-certified lab-grown diamonds in every shape, filtered by carat, color, clarity and cut, at roughly 40–60% less than comparable natural stones.
More on diamond quality: Cut, Clarity, Color, Carat weight, and diamond certificates.