691.5 Mohs = 6.78 HRC
| Mohs | HRC |
|---|---|
| 676.5 Mohs | 6.63 |
| 681.5 Mohs | 6.68 |
| 686.5 Mohs | 6.73 |
| 691.5 | 6.78 |
| 696.5 Mohs | 6.83 |
| 701.5 Mohs | 6.88 |
| 706.5 Mohs | 6.93 |
691.5 Mohs = 6.78 HRC
1 HRC ≈ 10.2 HV · 1 HRB ≈ 1.8 HV · 1 Mohs ≈ 0.1 HV — approximate; real conversions vary by material per ASTM E140