Gallery
The eleven diamond shapes
Every shape drawn to scale at the same carat weight, so you can see which ones spend their weight on size and which spend it on depth.
Every stone on this page weighs exactly one carat and every one is drawn to the same scale. Retailers’ shape charts almost never do this — they draw each shape at whatever size fits the grid, which hides the one comparison worth making. At the same weight and the same price bracket, these shapes are genuinely different sizes to look at.
One carat, every shape, same scale
Emerald cut
7.19 × 5.13 mm
36.9 mm² seen
Step cuts show clarity plainly — there is nowhere for an inclusion to hide.
Oval
8.01 × 5.72 mm
36.0 mm² seen
Reads larger than a round of the same weight, because more of the weight is in the outline.
Radiant
6.74 × 5.18 mm
34.9 mm² seen
Brilliant faceting in a rectangular outline.
Marquise
10.42 × 5.34 mm
33.4 mm² seen
The largest face-up area of any shape for a given weight.
Round brilliant
6.44 × 6.44 mm
32.5 mm² seen
The reference shape. Everything else is compared to it.
Heart
6.56 × 6.56 mm
32.3 mm² seen · -1% vs round
Width is measured across the two lobes.
Cushion
6.02 × 5.47 mm
31.3 mm² seen · -4% vs round
Also carries weight in the depth.
Asscher
5.69 × 5.69 mm
30.7 mm² seen · -6% vs round
A square emerald cut, in effect.
Pear
8.67 × 5.59 mm
29.1 mm² seen · -11% vs round
Measured point to point along the long axis.
Princess
5.49 × 5.49 mm
28.6 mm² seen · -12% vs round
Deep for its width, so a princess looks smaller face-up than its weight suggests.
Trillion
7.42 × 7.42 mm
27.5 mm² seen · -15% vs round
Shallow, so it spreads wide for its weight.
Ranked by how big they look
Face-up area is the number that answers “will it look big”, and it does not rank the same way as carat weight. The shapes at the top of this table spend their weight on the outline; the ones at the bottom spend it on depth, below the girdle, where nobody ever sees it.
| Shape | Size at 1 ct | Face-up area | vs round | Typical depth |
|---|---|---|---|---|
| Emerald cut | 7.19 × 5.13 mm | 36.9 mm² | +13% | 66% of width |
| Oval | 8.01 × 5.72 mm | 36.0 mm² | +11% | 62% of width |
| Radiant | 6.74 × 5.18 mm | 34.9 mm² | +7% | 69% of width |
| Marquise | 10.42 × 5.34 mm | 33.4 mm² | +3% | 60% of width |
| Round brilliant | 6.44 × 6.44 mm | 32.5 mm² | — | 62% of width |
| Heart | 6.56 × 6.56 mm | 32.3 mm² | -1% | 60% of width |
| Cushion | 6.02 × 5.47 mm | 31.3 mm² | -4% | 68% of width |
| Asscher | 5.69 × 5.69 mm | 30.7 mm² | -6% | 68% of width |
| Pear | 8.67 × 5.59 mm | 29.1 mm² | -11% | 60% of width |
| Princess | 5.49 × 5.49 mm | 28.6 mm² | -12% | 73% of width |
| Trillion | 7.42 × 7.42 mm | 27.5 mm² | -15% | 43% of width |
Sizes are estimated from the standard trade weight-estimation factors for a normally cut stone. Real stones vary — a deeply cut round can be several tenths of a millimetre smaller face-up than a shallow one of identical weight, which is exactly why two one-carat stones can look like different sizes.
This is a page about size, not price
There is no pricing on this page, and there will not be. Diamond prices come from wholesale sheets that are licensed rather than published, they move, and they depend on a graded report that describes the individual stone. A price invented here would look authoritative and be worth nothing, which is worse than saying so.
What is safe to say is structural, and it is this: fancy shapes generally cost less per carat than rounds, because cutting a round wastes more of the rough. So a shape from the top of that table can be both larger to look at and cheaper than the round directly below it at the same weight. That is a real trade-off you can take to a shop — unlike a number this site would have had to make up.
Common questions
How many millimetres is a 1 carat diamond?
A well-cut one-carat round brilliant measures about 6.44 mm across. Other shapes at the same weight vary from roughly 5 to 10 mm on their long axis — see the table above, or use the size calculator for any weight.
Which diamond shape looks the biggest?
Marquise, at the same carat weight, followed by pear and oval. All three are elongated and comparatively shallow, so more of the weight sits in the outline you can see. Princess, cushion and asscher look smallest for their weight, because they are cut deep.
Is a 2 carat diamond twice the size of a 1 carat?
No. Carat is a unit of weight, and weight grows with the cube of the dimensions — so doubling the weight makes the stone about 26% wider, not 100%. A one-carat round is around 6.4 mm across and a two-carat round is around 8.1 mm.