The exposed diamonds on the surface of each segment do the cutting, using abrasive action to slice through material as the blade rotates at high speeds. As the diamonds at the surface become dull through use, the matrix begins to shed away to release the worn diamond crystals and expose new, sharp diamonds embedded within the matrix. The most important fact to know is that the hardness of the matrix controls how quickly a blade wears. Here is the basic rule: A diamond blade used to cut soft, abrasive materials (such as uncured, green concrete) should have a hard metal bond so the exposed diamonds are fully utilized before they shed away. Conversely, a blade for cutting hard, nonabrasive concrete should have a soft bond to allow for easier erosion of the matrix, which will ensure exposure of new, sharp diamonds when you need them.