| Millimeters | Inches | Rounded to Nearest 100th | Approximate Size * |
| 3 mm | 0.1181102362206 | 0.12 |  |
| 4 mm | 0.1574803149608 | 0.16 |  |
| 5 mm | 0.196850393701 | 0.20 |  |
| 6 mm | 0.2362204724412 | 0.24 |  |
| 7 mm | 0.2755905511814 | 0.28 |  |
| 8 mm | 0.3149606299216 | 0.31 |  |
| 9 mm | 0.3543307086618 | 0.35 |  |
| 10 mm | 0.393700787402 | 0.39 |  |
| 11 mm | 0.43307086614220003 | 0.43 |  |
| 12 mm | 0.4724409448824 | 0.47 |  |
| 13 mm | 0.5118110236226 | 0.51 |  |
| 14 mm | 0.5511811023628 | 0.55 |  |
| 15 mm | 0.590551181103 | 0.59 |  |
| * Sizes of graphic hearts shown are approximate and meant as a visual aid only. These graphics are based on gemstone heart size rounded to the nearest hundredth of an inch and are therefore not exact. Additionally, their appearance may alter slightly based on your screen resolution. | |||