Knoop hardness (KH),

Definition of Knoop hardness (KH):

1. Material hardness test in which the depth (and not the area) of indent caused by the impact of a highly polished and elongated pyramidical (pointed rhombohedral) diamond is measured. KH is expressed as a ratio of the applied force in kilograms and the depth of ■■■■■■■■■■■ in millimeters.