Book 27, Question 112
Why are diamonds on saw blades and drill bits?
Diamond is the hardest known natural material, so it can cut or grind almost anything.
Tiny diamonds glued to the edge of a saw blade cut through stone, concrete, and tile. Drill bits tipped with diamonds can reach deep into rock. Sandpapers use other hard crystals, like garnet and corundum. The crystals wear away the softer material and stay sharp.