Diamond size comparison
A one-carat round brilliant is about 6.5 mm across — the width of a pencil. Carat is weight, not width: doubling the carat adds only about a quarter to the visible diameter. Calibrate once with a bank card and see every size at true scale on your own screen.
1 Calibrate with a bank card
Drag until the outline matches any bank card (85.6 mm). Done it before on this device? We remembered.
2 True size, on your screen
1,0 ct
6,4 mm
5-cent coin
21,25 mm
Sizes are for round brilliants of typical proportions; a well-cut stone can look larger than a heavier, deeper one. On a finger, spread matters more than weight — which is why cut is the one C never to save on.
| Carat | ⌀ mm | Visible size vs 1 ct |
|---|---|---|
| 0,3 | 4,3 | 45% |
| 0,5 | 5,1 | 64% |
| 0,7 | 5,7 | 79% |
| 1,0 | 6,4 | 100% |
| 1,5 | 7,4 | 134% |
| 2,0 | 8,1 | 160% |