The use of diamond in abrasives is due to its hardness. Diamond is one of the hardest naturally occurring substances on Earth, and its hardness makes it ideal for use in abrasive applications. When diamond is used as an abrasive, it can cut through and grind down even the toughest materials, including metals and ceramics. Additionally, diamond is incredibly durable, so it can withstand the wear and tear of abrasive applications better than many other materials.