The diamond grit size, or
diameter of the diamond particles, plays a significant role in quality of the cut. The surface finish quality, smoothness, and amount of chipping are all affected by the diamond grit size. The finer the diamond grit, the smoother the cut will be and the rougher the diamond grit, the coarser the resulting cut. Coarse diamond grits are frequently used where a smooth finish and chipping is not a concern.
The diamond grit size also plays a role in the cutting speed. Because coarse diamond grit size has larger diamond particles than finer grit, the diamond particles are able to remove material more quickly, producing faster cutting speeds. A blade with a grit size appropriate for the material being cut will provide an acceptable finish at the best cutting speed.
Coarse diamond grit (#20 - #60) is often used for masonry, concrete, and natural stone while medium diamond grit (#80 - #220) is frequently ideal for ceramic, porcelain, glass, and other brittle materials. Fine diamond grit (#240 - #400) is used for extremely smooth cutting, polishing, and grinding. Some blades may also have a combination of coarse and fine grit sizes that will allow for faster cutting speeds while maintaining smooth and chip free cuts.