Diamond size chart, to scale.
Pick a shape and slide through carat weights to see how big each diamond looks face-up, with its approximate millimetre dimensions.
Every size, in proportion.
All sizes are drawn on the same scale, so you can see how the face-up size grows with carat weight. Tap any stone to load it above.
MM to carat conversion chart.
| Carat | Size (mm) | Area |
|---|
Size questions, answered.
These figures are typical averages. Two diamonds of the same carat weight can measure differently depending on how they are cut.
Is carat a measure of size?
No — carat is a unit of weight (1 carat = 0.2 grams). Millimetre dimensions describe the visible size. A stone cut deep carries more of its weight below the girdle, so it can look smaller face-up than a shallower stone of the same carat weight.
Why do elongated shapes look bigger?
Oval, pear and marquise diamonds spread their weight over a longer outline, so they usually show more face-up area than a round diamond of the same carat weight.
How accurate is the “actual size” view?
It uses your screen's CSS millimetre, which is close on most devices but not exact. Use the 10 mm scale bar as a guide, or hold a ruler to the screen to compare.
Are lab-grown diamonds the same size as mined ones?
Yes. Lab-grown and mined diamonds have the same density, so a given carat weight and cut gives the same dimensions.