The pillow cut,sized to scale.Carat to millimetres.
A soft square with rounded corners, the cushion is measured by its side length in millimetres. This chart converts each carat to real dimensions from our own stones.
Why carat isn't the same as size.
Carat measures weight, not dimensions. The size you actually see is the stone's measurement in millimetres — and two diamonds of the same carat can look different sizes depending on how they are cut.
A shallow, well-spread stone shows more face-up area; a deep-cut one hides weight underneath. So when comparing diamonds, compare the millimetre dimensions, not just the carat weight.
"The number that decides how big a diamond looks isn't the carat — it's the measurement in millimetres."
The chart below gives you both, so you can picture the real size before you choose.
What makes the cushion special.
Gently curved corners give the cushion its pillowy look and make it durable, with no sharp points to chip.
Larger facets give a softer, chunkier fire than a round — a vintage, candle-lit character.
Cushions come near-square or gently elongated; the ratio sets whether it reads round or long.
Brilliant faceting masks small inclusions, so eye-clean VS stones are easy to find.
What each size actually looks like.
These cushion shapes are drawn to relative scale from real face-up dimensions. Notice how gently size grows — a 2 carat is larger than a 1 carat, but not twice the size.
Drawn to relative scale for a well-cut cushion. On-screen sizes are proportional, not literal millimetres — see the chart below for exact dimensions.
Cushion Cut carat to millimetre chart.
Approximate face-up dimensions for a well-cut cushion. Sizes marked "Measured" reflect our own diamond measurements; larger sizes are extrapolated to the same proportions. Individual stones vary with cut and depth.
| Carat Weight | Size (mm) | L/W Ratio | Source |
|---|---|---|---|
| 0.25 ct | 3.6 mm | 1.00 | Measured |
| 0.50 ct | 4.5 mm | 1.00 | Measured |
| 0.75 ct | 5.2 mm | 1.00 | Measured |
| 1.00 ct | 5.7 mm | 1.00 | Measured |
| 1.25 ct | 6.1 mm | 1.00 | Approx. |
| 1.50 ct | 6.5 mm | 1.00 | Approx. |
| 1.75 ct | 6.9 mm | 1.00 | Approx. |
| 2.00 ct | 7.2 mm | 1.00 | Approx. |
| 2.50 ct | 7.7 mm | 1.00 | Approx. |
| 3.00 ct | 8.2 mm | 1.00 | Approx. |
| 4.00 ct | 9.0 mm | 1.00 | Approx. |
| 5.00 ct | 9.7 mm | 1.00 | Approx. |
Choosing the right proportions.
Two cushions of the same carat can look different depending on their length-to-width ratio. It comes down to taste — here are the main looks.
The classic pillow — soft, symmetrical and romantic.
A gently elongated cushion — a touch of length while staying soft.
A longer cushion for a more distinctive, finger-lengthening look.
Four things worth knowing first.
Beyond size, a few cushion-specific pointers help you choose a stone that looks its best.
A ~1.00 cushion is the classic pillow; 1.10–1.20 adds gentle length. Pick the outline first.
Faceting hides inclusions well, so an eye-clean VS1–VS2 looks flawless at good value.
Cushions can carry a little warmth, which suits yellow and rose gold beautifully; choose higher colour for white metal.
Rounded corners make the cushion one of the most wear-friendly shapes for daily rings.
How the setting changes the size you see.
The same stone can look bigger or smaller depending on how it is set. If maximising visual size matters, the setting is as important as the carat weight.
A solitaire shows the true size; a halo frames it to read larger; a three-stone setting stretches the look along the finger. Choosing well means you can often get the presence you want without moving up in carat.
Browse cushion diamonds by size.
Found your size? Go straight to the collection — every stone IGI certified and lab grown.
Cushion size questions, answered.
The questions we hear most about cushion diamond sizing. If yours isn't here, just ask.
Chat on WhatsAppCompare sizes across every shape.
Still choosing a shape? Compare all cuts side by side →
Everything you need to choose with confidence.
Find your perfect cushion.
Every cushion is IGI certified and made to order, in the exact carat, ratio, and setting you choose. Not sure which size suits the hand? Tell us and we'll guide you.