Which diamond shape looks the biggest per carat?
Elongated shapes look largest for their weight. Marquise, pear and oval diamonds spread more surface area face-up than a round of the same carat, so they appear noticeably bigger on the finger.
Round brilliant
Fifty-seven or fifty-eight facets engineered purely for light return, and the only shape with a laboratory cut grade. A one-carat round measures about 6.5mm across. It commands roughly a fifteen to thirty percent premium over fancy shapes because demand is highest and cutting a round wastes the most rough crystal. Choose it if sparkle matters more than size-per-dollar.
Oval and pear
Both are elongated brilliants that spread wide face-up — an oval runs about 8.1mm by 5.4mm at one carat, a pear about 9.1mm by 5.5mm. They read larger than a round of the same weight and cost less per carat. Watch for the bow-tie, a dark band across the centre caused by uneven pavilion facets; a good cutter minimises it, and it is only visible in real images rather than on a certificate.
Cushion and princess
Cushion is a softened square with rounded corners and a pillowy, romantic sparkle; princess is a sharp-cornered square with crisp, mosaic-like flashes. Both hold weight in their depth, so a one-carat cushion is about 6mm and a princess about 5.6mm — smaller face-up than a round. In exchange they typically cost noticeably less per carat, and their brilliant faceting hides inclusions well.
Emerald, Asscher and radiant
Emerald and Asscher are step cuts: long parallel facets that produce broad flashes and a glassy hall-of-mirrors look rather than fine sparkle. Because those facets are open, clarity and colour show more, so aim for VS2 or better. Radiant combines an emerald outline with brilliant faceting, giving square-ish geometry with round-cut fire — a strong value shape.
Marquise, heart and less common outlines
Marquise is the most dramatic size-per-carat shape, stretching about 10.4mm long at one carat, and it elongates the finger. Hearts require exceptional symmetry to look right and are best above 0.75 carats so the cleft reads clearly. Rarer outlines like trillion, baguette and old-mine cuts are usually used as accents or in bespoke work.
Shape, setting and price together
Shape also decides which settings work. Pointed shapes such as pear and marquise need V-prongs to protect the tips; ovals suit east-west and hidden-halo designs; emeralds look natural in bezels and three-stone layouts. Use the True Carat estimator to switch shape and setting side by side — the price and the rotatable 3D model both update, with a downloadable model and PDF estimate at the end.
Common questions
Which diamond shape is the cheapest?
Round brilliants carry the highest price per carat because they are the most in demand and waste the most rough. Oval, cushion, emerald, radiant, pear and marquise shapes generally cost less per carat for equivalent grades.
What is the most popular diamond shape for engagement rings?
Round brilliant is still the most popular by a wide margin, followed by oval and then cushion. Emerald and radiant cuts have grown quickly in recent years.
Do all diamond shapes get a cut grade?
No. Laboratories issue an overall cut grade for round brilliants only. Fancy shapes are assessed on polish and symmetry, so you need to judge table, depth, outline and any bow-tie effect yourself or from images.
Which diamond shape hides inclusions best?
Brilliant-faceted shapes — round, oval, cushion, pear, marquise and radiant — scatter light and mask small inclusions well, so SI clarity often faces up clean. Step cuts like emerald and Asscher have large open facets that show inclusions more readily, so VS clarity or better is safer.