Lapidaries use slab and trim saws. The difference is the size blade they use. Trim saws have small, thin blades that remove a minimum of material. Slab saw blades are thicker, because they are designed to do heavier cutting. Trim saws use 4 to 6 inch blades that run between .004 and .012 inches thick.
Diamond blades are like a revolving finger nail file.
They will not cut fingers, but they will give you a creative manicure if you are not careful. The exceptions to this are the very thin blades of .004 to .006 inches. At this size they will cut fingers. They are also much easier to bend, or dish, than a heavier blade. So unless you are cutting very expensive material, it is best to use a slightly thicker blade.