664.5 Mohs = 6.51 HRC
| Mohs | HRC |
|---|---|
| 649.5 Mohs | 6.37 |
| 654.5 Mohs | 6.42 |
| 659.5 Mohs | 6.47 |
| 664.5 | 6.51 |
| 669.5 Mohs | 6.56 |
| 674.5 Mohs | 6.61 |
| 679.5 Mohs | 6.66 |
664.5 Mohs = 6.51 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