| 1 | With regard to hardness, the diamond is in a class by itself. | |
| 2 | The secret to a diamond's hardness is its atomic arrangement. | |
| 3 | Diamonds are forever, and so is their extreme hardness. | |
| 4 | Hammer hardness is something that could be adjusted in the maintenance of an actual piano. | |
| 5 | Of course, all this needs to be adjusted according to the actual hardness of the chocolate. |