Which material is commonly used as an abrasive due to its hardness rating?

The material most commonly used as an abrasive due to its hardness rating is diamond. Diamonds are renowned for their exceptional hardness, ranking at the top of the Mohs scale with a rating of 10. This remarkable hardness makes them especially effective for cutting, grinding, and drilling applications.

While quartz and sapphire are also hard materials—Quartz ranks at a 7 on the Mohs scale and sapphire at a 9—they do not possess the same level of hardness as diamond. Iron, on the other hand, is significantly softer and not suitable for use as an abrasive. Therefore, diamond is the premier choice for applications that require intense abrasion, making it the correct answer in this context.