666.5 Mohs = 6.53 HRC
| Mohs | HRC |
|---|---|
| 651.5 Mohs | 6.39 |
| 656.5 Mohs | 6.44 |
| 661.5 Mohs | 6.49 |
| 666.5 | 6.53 |
| 671.5 Mohs | 6.58 |
| 676.5 Mohs | 6.63 |
| 681.5 Mohs | 6.68 |
666.5 Mohs = 6.53 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