640.5 Mohs = 6.28 HRC
| Mohs | HRC |
|---|---|
| 625.5 Mohs | 6.13 |
| 630.5 Mohs | 6.18 |
| 635.5 Mohs | 6.23 |
| 640.5 | 6.28 |
| 645.5 Mohs | 6.33 |
| 650.5 Mohs | 6.38 |
| 655.5 Mohs | 6.43 |
640.5 Mohs = 6.28 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