How to Choose a Lab-Grown Diamond Shape: 10 Shapes Compared on Size, Sparkle, Clarity and Setting

Updated October 19, 2026

The short answer: Choose the shape before you choose the grades, because shape changes everything after it. Elongated brilliant shapes (oval, pear, marquise) look the largest for their weight. Square, deep cuts (princess, Asscher, many cushions) look the most compact. Step cuts (emerald, Asscher) show color and inclusions more, so GIA suggests about VS 2 clarity and G color or above if you want them to look clean and colorless. Brilliant shapes (round, oval, radiant, princess and others) are more forgiving of both. Only round brilliants get an overall cut grade, so for any other shape you'll judge the cut from its ratio, symmetry and video. Points and sharp corners (pear, marquise, princess, heart) need a setting that protects them.

The comparison table and the shape-by-shape notes below use two kinds of source. Advice on appearance and setting comes from GIA's published shape guidance. Millimeter sizes are medians from the IGI and GIA reports on white loose laboratory-grown diamonds in our catalog, measured for our size chart on October 11, 2026.

Shape vs. cut style: two different decisions

GIA separates the two. Shape is the outline you see from above: round, oval, pear and so on. Cut style is how the facets are arranged. Most shapes are cut in one of two styles:

  • Brilliant cuts have many small triangular and kite-shaped facets. GIA says this busier pattern gives more brilliance and fire, and that it hides inclusions and body color better, which makes brilliant cuts more forgiving of lower color and clarity grades. Round, oval, pear, marquise, heart, princess and radiant are brilliant-style.
  • Step cuts have long, parallel, trapezoid-shaped facets that create what GIA calls a "hall of mirrors" look, with a gleam more than a sparkle. GIA says their larger, open facets show color and clarity more. Emerald and Asscher are step cuts.

Cushions come in both. GIA describes a "brilliant" cushion with larger facets and a softer sparkle, and a "modified" cushion with extra facets and a "crushed ice" look. The facet pattern can matter as much as the outline, so watch the video, not just the shape name.

Laboratory-grown and mined diamonds behave the same way here. Under the FTC's definition (16 CFR 23.12), both are diamond, so shape and cut style affect a laboratory-grown stone exactly as they affect a mined one.

How we compared the shapes

We compared each shape on the six things that actually change your decision:

  1. Face-up size per carat. The median length × width at 1.00 carat from real report measurements in our catalog.
  2. Cut style. Brilliant or step, which tells you how forgiving the shape is of color and inclusions.
  3. Whether the report has an overall cut grade. Rounds do. Most fancy shapes don't, so you judge cut yourself.
  4. Typical length-to-width ratio, for shapes where ratio changes the look, from GIA's research and shape guidance.
  5. Visual traits to check, such as the bow-tie in elongated brilliants or the X pattern in an Asscher.
  6. Setting needs. Which points or corners need protecting, per GIA.

We don't rank shapes. There's no "right" one, only the one that suits the person wearing it and the setting it's going into.

Lab-grown diamond shapes compared

Shape Cut style Median size at 1.00 ct (our catalog) Overall cut grade on report? Color & clarity sensitivity Setting care Browse
Round Brilliant 6.5 mm diameter Yes (IGI: Ideal to Fair; GIA: Excellent to Poor) Most forgiving Few constraints Round
Oval Brilliant 8.2 × 5.6 mm Usually no Forgiving; check bow-tie Few constraints Oval
Pear Brilliant 9.0 × 5.5 mm Usually no Forgiving; check point and bow-tie Protect the point (V-prong or bezel) Pear
Marquise Brilliant 10.9 × 5.1 mm Usually no Points hide small inclusions; check bow-tie Protect both points (V-prongs) Marquise
Radiant Brilliant (cropped corners) 7.1 × 4.9 mm Usually no Forgiving ("crushed ice") Cropped corners help durability Radiant
Cushion Brilliant or modified brilliant 6.7 × 5.3 mm Usually no Depends on facet style Few constraints Cushion
Princess Brilliant (square) 5.5 × 5.4 mm Usually no Corners can hide inclusions Protect corners (V-prongs or bezel) Princess
Heart Brilliant 6.9 × 6.1 mm Usually no Check point; symmetry is critical Protect the point; prongs on the lobes Heart
Emerald Step 6.8 × 4.7 mm Usually no Shows color and inclusions (GIA: VS 2 / G or above) Corners are cropped Emerald
Asscher Step (square) 5.5 × 5.5 mm Usually no Shows color and inclusions (GIA: VS 2 / G or above) Double prongs common on large stones Asscher

Sizes are medians for white (D to H) stones within 0.03 carat of 1.00 ct. A specific stone can measure a little more or less depending on depth and ratio, so always check the measurements on its listing and report. Hexagons, kites, old European cuts and other outlines are in specialty shapes.

Shape by shape

Round brilliant

GIA calls the round brilliant the shape with the most brightness, and it's the only shape that gets an official GIA cut grade. IGI also prints a cut grade for rounds on a scale from Ideal to Fair. That makes rounds the easiest shape to compare: two rounds with the same cut, color and clarity grades will look broadly similar, so you can shop on the report and measurements. The trade-off is size. At 1.00 carat our median round is 6.5 mm across, which covers less area face-up than a same-weight oval, pear or marquise.

Oval

An oval is a stretched brilliant. It sparkles like a round and looks bigger for its weight. Our 1.00 ct median is 8.2 × 5.6 mm, about 8% more face-up area than the median round. GIA's shape guide says most ovals fall between 1.30 and 1.40 length-to-width, and its Gems & Gemology research gives a wider design range of 1.2 to 1.7. Every brilliant oval shows some dark bow-tie across the middle. You want one that stays soft as the stone moves. Our oval buying guide covers ratio and bow-tie in detail.

Pear

A pear combines a rounded end with a single point. GIA's research says pears usually run 1.3 to 1.8 length-to-width. Like ovals, pears can show a bow-tie. GIA notes the point needs a secure setting, such as a V-prong or bezel, to help prevent chipping. A pear can be worn point up, point down or at an angle, so decide that with your jeweler. It changes the look more than you'd expect. GIA's holiday buying guide also suggests checking the point for inclusions and color concentration, and the "wings" on either side for symmetry.

Marquise

At 10.9 mm long for a median 1.00 ct, the marquise has the longest outline per carat in our catalog. GIA says it gives the illusion of a larger stone. The G&G range is 1.5 to 2.5 length-to-width. Both points are vulnerable to chipping, so GIA recommends protective settings such as V-prongs. Symmetry matters more than usual: uneven sides or points that don't line up are easy to see. GIA notes the points can hide small inclusions well, but its marquise guide also says most marquises show some bow-tie, and that one with no bow-tie at all is often dull.

Radiant

A radiant has the cropped-corner outline of an emerald cut with brilliant faceting. GIA counts 70 facets and describes a "crushed ice" look that helps hide inclusions and warmer color, so it's more forgiving than an emerald or Asscher. The cropped corners also help it resist chipping. Radiants come in square and rectangular outlines, so check the ratio. Our 1.00 ct median of 7.1 × 4.9 mm reflects the elongated stones in our catalog.

Cushion

GIA describes the cushion as a cross between a round and a princess, with rounded corners and a soft, vintage feel. It also notes cushions' slightly deeper proportions can make them face up smaller than other shapes of the same weight. Because "cushion" covers both larger-facet brilliant and crushed-ice modified styles, as well as square and elongated outlines, two cushions can look completely different. Our 1.00 ct median of 6.7 × 5.3 mm is elongated, but at 0.50 ct the median is nearly square. Choose on the video and the ratio, not the name.

Princess

A princess is a square brilliant. GIA notes its sharp corners are good at hiding inclusions, especially inclusions located in the corners, so you may not need as high a clarity grade. Its deep pavilion puts weight below the girdle, so a 1.00 ct princess faces up at about 5.5 mm square in our catalog, roughly a millimeter narrower than a 1.00 ct round. GIA recommends V-shaped prongs or a bezel to protect the corners.

Heart

GIA says a heart needs precise symmetry: matching halves, smooth lobes, a clear cleft and a sharp tip. It also says hearts should be about 0.50 carat or larger to show the shape clearly, and most hearts in the U.S. have a length-to-width ratio of about 1:1. Settings should protect the point and put prongs on the lobes, not in the cleft, so the outline reads as a heart.

Emerald

The emerald is the classic rectangular step cut. Its long, open facets give the hall-of-mirrors gleam and show clarity and color more readily. GIA recommends VS 2 clarity and G color or above, and higher grades for stones of about 2 to 3 carats and up. If you love the outline but want more sparkle and more forgiveness, compare it with a radiant. Our emerald and Asscher guide goes deeper.

Asscher

The Asscher is a square step cut with a high crown, small table and deep pavilion that draws the eye toward the center, often showing an "X" pattern face-up. GIA gives the same VS 2 / G or above guidance as for emerald cuts, especially over 2 to 3 carats. For larger Asschers, GIA notes double prongs at the beveled corners are common for added security.

How shape changes what you pay attention to on a budget

We don't publish price comparisons between shapes, because prices change daily and vary by stone. You can compare price per carat on our listings yourself. What shape does change is which grades are worth paying for:

  • Choosing a step cut? Put more of your budget into clarity and color. GIA's VS 2 / G guidance for emerald and Asscher exists because those cuts show more.
  • Choosing a brilliant fancy shape? You can often accept a lower clarity or color grade without seeing a difference face-up, especially in princess corners or marquise points. Confirm it on the 360° video.
  • Want the most visible size for the weight? Look at oval, pear and marquise first, and compare measurements rather than carat.
  • Want an easy comparison? Rounds are the only shape with an overall cut grade, so you can shop on the report with fewer judgment calls.

Before you choose: a short checklist

  1. Decide the shape with your jeweler first if the stone is going into a custom setting. Pointed shapes need specific prongs. Our guide to buying a loose stone for a custom setting lists what to send them.
  2. Filter by millimeters, not just carat. Use the size chart to see what each weight looks like in your shape.
  3. Check the ratio on elongated shapes. Work it out from the length and width on the report.
  4. Watch the 360° video, available on most listings, for bow-tie, symmetry and how the facet pattern looks in motion.
  5. Verify the report on the lab's own site. Our guide to reading an IGI report walks through each line, including why many fancy shapes have no cut grade.

Browse all laboratory-grown diamonds or start with a shape above.

Frequently asked questions

Which lab-grown diamond shape looks biggest for its carat weight? Elongated brilliant shapes. In our catalog, a median 1.00 ct marquise is about 10.9 mm long, a pear about 9.0 × 5.5 mm and an oval about 8.2 × 5.6 mm, compared with 6.5 mm for a round. GIA also notes that elongated shapes give the illusion of greater size.

Which shapes hide inclusions and color best? Brilliant cuts, according to GIA, because their many small facets mask inclusions and body color. GIA singles out radiant cuts as forgiving and notes that princess corners and marquise points can hide small inclusions. Step cuts such as emerald and Asscher show more.

Why doesn't my oval, pear or emerald report have a cut grade? GIA gives its overall cut grade only to round brilliants, and IGI's cut grade line appears on rounds too. Fancy-shape reports show polish and symmetry instead, so you judge their cut from proportions, ratio and the video.

Which shapes are more likely to chip? GIA says shapes with points or sharp corners (pear, marquise, princess and the tip of a heart) need protective settings such as V-prongs or a bezel. Radiant and emerald cuts have cropped corners, which GIA notes help prevent chipping.

Is a lab-grown diamond shape different from a mined diamond of the same shape? No. Both are diamond under the FTC's definition, and shape and cut style affect them the same way. What matters for any individual stone is its measurements, grades and how it looks on video.

What is the most popular diamond shape? GIA says the round brilliant accounts for the majority of diamonds sold. Popularity shouldn't decide for you, though. Choose the outline the wearer likes, then use this guide to pick the grades that matter for that shape.

Sources

Reviewed October 19, 2026 against the sources above. Inventory changes daily, so verify the report number and watch the current video for any stone you consider.

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