The heart,sized with care.Carat to millimetres.
A brilliant cut shaped as a symbol of love, the heart is measured by length and width in millimetres — roughly equal. This chart uses 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 heart special.
The heart outline — the cleft and point — reads most clearly at around a carat or larger; very small hearts lose definition.
A crisp cleft, even lobes and a sharp point are everything — symmetry is what makes a heart look like a heart.
The bottom tip is delicate; a prong at the point shields it from chipping.
Brilliant faceting masks small inclusions, so eye-clean VS stones are easy to find.
What each size actually looks like.
These heart 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 heart. On-screen sizes are proportional, not literal millimetres — see the chart below for exact dimensions.
Heart Cut carat to millimetre chart.
Approximate face-up dimensions for a well-cut heart. 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 | 4.3 × 4.0 mm | 1.08 | Measured |
| 0.50 ct | 5.5 × 5.1 mm | 1.08 | Measured |
| 0.75 ct | 6.3 × 5.8 mm | 1.08 | Measured |
| 1.00 ct | 6.9 × 6.4 mm | 1.08 | Measured |
| 1.25 ct | 7.4 × 6.9 mm | 1.08 | Approx. |
| 1.50 ct | 7.9 × 7.3 mm | 1.08 | Approx. |
| 1.75 ct | 8.3 × 7.7 mm | 1.08 | Approx. |
| 2.00 ct | 8.7 × 8.1 mm | 1.08 | Approx. |
| 2.50 ct | 9.4 × 8.7 mm | 1.08 | Approx. |
| 3.00 ct | 10.0 × 9.2 mm | 1.08 | Approx. |
| 4.00 ct | 11.0 × 10.2 mm | 1.08 | Approx. |
| 5.00 ct | 11.8 × 10.9 mm | 1.08 | Approx. |
Choosing the right proportions.
Two hearts of the same carat can look different depending on their length-to-width ratio. It comes down to taste — here are the main looks.
A little longer than wide — a slender, graceful heart.
The balanced heart — as wide as it is long, clearly readable and symmetrical.
A fuller, broader heart — plump and generous.
Four things worth knowing first.
Beyond size, a few heart-specific pointers help you choose a stone that looks its best.
Below about 0.75 ct the heart shape is hard to read, especially from a distance. A carat and up shows it best.
Even lobes, a defined cleft and an aligned point decide whether the heart looks balanced — more than any grade.
A prong at the point guards the most fragile part and keeps the outline sharp.
Warmth can gather at the tip; a slightly higher colour grade keeps it bright in white metal.
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 heart diamonds by size.
Found your size? Go straight to the collection — every stone IGI certified and lab grown.
Heart size questions, answered.
The questions we hear most about heart 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 heart.
Every heart 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.