How big isan oval, really?Carat to millimetres.
An oval's true size is its length × width in millimetres. This chart converts every popular carat weight to real dimensions, using our own diamond measurements.
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 oval special.
Its elongated outline spreads more surface across the finger, so an oval appears roughly 10–15% larger than a round of the same carat.
The long axis visually lengthens and slims the finger — a key reason it is so popular for engagement rings.
Most ovals show a faint darker band across the centre. Excellent symmetry keeps it subtle.
Brilliant faceting masks small inclusions, so an eye-clean VS1–VS2 oval is easy to find.
What each size actually looks like.
These oval 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 oval. On-screen sizes are proportional, not literal millimetres — see the chart below for exact dimensions.
Oval Cut carat to millimetre chart.
Approximate face-up dimensions for a well-cut oval. 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 | 5.0 × 3.5 mm | 1.43 | Measured |
| 0.50 ct | 6.3 × 4.4 mm | 1.43 | Measured |
| 0.75 ct | 7.3 × 5.1 mm | 1.43 | Measured |
| 1.00 ct | 8.0 × 5.6 mm | 1.43 | Measured |
| 1.25 ct | 8.6 × 6.0 mm | 1.43 | Approx. |
| 1.50 ct | 9.2 × 6.4 mm | 1.43 | Approx. |
| 1.75 ct | 9.6 × 6.7 mm | 1.43 | Approx. |
| 2.00 ct | 10.1 × 7.1 mm | 1.43 | Approx. |
| 2.50 ct | 10.9 × 7.6 mm | 1.43 | Approx. |
| 3.00 ct | 11.5 × 8.1 mm | 1.43 | Approx. |
| 4.00 ct | 12.7 × 8.9 mm | 1.43 | Approx. |
| 5.00 ct | 13.7 × 9.6 mm | 1.43 | Approx. |
Choosing the right proportions.
Two ovals of the same carat can look different depending on their length-to-width ratio. It comes down to taste — here are the main looks.
Fuller and softer, closer to a round, with a little less lengthening effect.
The balanced, most popular look — elegantly elongated without being narrow.
Longer and more slender, for the strongest finger-lengthening effect.
Four things worth knowing first.
Beyond size, a few oval-specific pointers help you choose a stone that looks its best.
Because ovals show a bow-tie, symmetry matters more than on a round. Excellent or Very Good symmetry keeps the outline even and the centre bright.
Ovals can hold a touch more warmth at the points. In white metal a slightly higher colour grade keeps it white; in yellow or rose gold a warmer grade blends in.
The faceting hides small inclusions, so an eye-clean VS1–VS2 looks flawless to the naked eye at far better value.
On slimmer fingers a 1 carat oval already reads generously; on broader hands 1.5–2 ct holds its presence.
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 oval diamonds by size.
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Oval size questions, answered.
The questions we hear most about oval diamond sizing. If yours isn't here, just ask.
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Everything you need to choose with confidence.
Find your perfect oval.
Every oval 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.