Ring Size Chart - sizes from Tiffany
| US Size | Inside circumference (mm) | |||
| 3 | 42.9 | |||
| 3.5 | 45.5 | |||
| 4 | 46.8 | |||
| 4.5 | 48.0 | |||
| 5 | 49.3 | |||
| 5.5 | 50.6 | |||
| 6 | 51.9 | |||
| 6.5 | 53.1 | |||
| 7 | 54.4 | |||
| 7.5 | 55.7 | |||
| 8 | 57.0 | |||
| 8.5 | 58.3 | |||
| 9 | 59.5 | |||
| 9.5 | 60.8 | |||
| 10 | 62.1 | |||
| 10.5 | 63.4 | |||
| 11 | 64.6 | |||
| 11.5 | 65.9 | |||
| 12 | 67.2 | |||
| 12.5 | 68.5 | |||
| 13 | 69.7 |
| US Size | Inside circumference (mm) | |||
| 3 | 42.9 | |||
| 3.5 | 45.5 | |||
| 4 | 46.8 | |||
| 4.5 | 48.0 | |||
| 5 | 49.3 | |||
| 5.5 | 50.6 | |||
| 6 | 51.9 | |||
| 6.5 | 53.1 | |||
| 7 | 54.4 | |||
| 7.5 | 55.7 | |||
| 8 | 57.0 | |||
| 8.5 | 58.3 | |||
| 9 | 59.5 | |||
| 9.5 | 60.8 | |||
| 10 | 62.1 | |||
| 10.5 | 63.4 | |||
| 11 | 64.6 | |||
| 11.5 | 65.9 | |||
| 12 | 67.2 | |||
| 12.5 | 68.5 | |||
| 13 | 69.7 |