Hardnester（YAMAMOTO）
| Hardnester | for general use | for precision tools | |
| Rockwell “C” 8 Hardness Set | Vickers 8 Hardness Set | Vickers 16 Hardness Set | |
| No. Ⅰ | HRC 20 | HV 200 | HV 200-250 |
| No. Ⅱ | HRC 30 | HV 300 | HV 300-350 |
| No. Ⅲ | HRC 40 | HV 400 | HV 400-450 |
| No. Ⅳ | HRC 50 | HV 500 | HV 500-550 |
| No. Ⅴ | HRC 55 | HV 600 | HV 600-650 |
| No. Ⅵ | HRC 60 | HV 700 | HV 700-750 |
| No. Ⅶ | HRC 65 | HV 800 | HV 800-850 |
| No. Ⅷ | HRC 67 | HV 900 | HV 900-950 |