| Material | Knoop |
| Hardness Scale | |
| Wood - Pine | 10 |
| Copper | 120 |
| Limestone | 125 - 150 |
| Marble | 140 - 180 |
| Slate | 140 - 250 |
| Porcelain Fixtures & China | 400 - 500 |
| Glass & Ceramic | 400 - 550 |
| Ceramic Wall Tile | 450 - 550 |
| Porcelain Wall Tile | 500 - 650 |
| Porcelain Floor Tile | 500 - 650 |
| Marble Style Porcelain Floor Tile | 500 - 650 |
| Granite Style Porcelain Floor Tile | 500 - 650 |
| Granite | 550 - 650 |
| Quartz | 820 |
| Common Tool Steel | 700 - 900 |
| Tungsten Carbide | 2,000 |
| Diamond | 7,000 |