A diamond grinding wheel is made of steel, with edges on which industrial diamond grains are applied. This makes the grinding disc extremely hard, so you effortlessly cut with your angle grinder through hard materials such as ceramic, tiles, natural stone or even concrete. The thickness of a diamond disc varies from 0.8 to 3.5 millimeters. For making slots, you obviously use a thicker disc than just for customizing gravel tiles for the garden.