The diamond is widely celebrated for its extreme durability, a reputation that often leads people to believe that it is completely indestructible. This perception of supreme strength is largely accurate when considering resistance to surface wear, yet it does not mean the stone is immune to all forms of damage. Understanding the true nature of a diamond’s durability requires separating its resistance to scratching from its vulnerability to impact. This distinction is paramount for anyone who owns or plans to purchase diamond jewelry in the future.
Understanding Diamond Hardness
Hardness in materials science is defined as a substance’s resistance to scratching or abrasion. This property is measured using the Mohs Hardness Scale, a qualitative scale that ranks minerals from 1 to 10 based on which mineral can scratch another. The diamond sits at the absolute peak of this scale, registering a 10, meaning it is the hardest known natural material on Earth.
This extreme hardness stems from the diamond’s unique crystalline structure, where carbon atoms are tightly bonded in a rigid, three-dimensional lattice. The difference in hardness between a diamond (10) and the next hardest mineral, corundum (9)—which includes rubies and sapphires—is not linear. In fact, a diamond is approximately four times harder than corundum in terms of absolute hardness measurements. This exceptional scratch resistance is why a diamond maintains its polish so well over time and is highly suitable for daily wear.
The Only Materials That Cause Scratches
The core truth about a diamond’s scratch resistance is that virtually no common material can abrade its surface. Since it ranks highest on the Mohs scale, any other gemstone, metal, or substance encountered in daily life—such as quartz, sand, or hardened steel—will be scratched by the diamond, not the other way around. The only common material that possesses the requisite hardness to scratch a diamond is another diamond. This diamond-on-diamond contact is the primary source of true surface scratches on jewelry. Industrial applications, such as cutting and polishing, rely on diamond dust or diamond-tipped tools to shape the stone, demonstrating that the only effective abrasive is the substance itself. While certain synthetic materials, like aggregated diamond nanorods or cubic boron nitride, can potentially scratch the hardest diamonds, these are not materials a consumer would encounter in a typical environment.
The Difference Between Scratching and Breaking
Despite its supreme hardness, a diamond is not indestructible; its durability must be viewed through two separate lenses: hardness and toughness. Hardness is resistance to scratching, but toughness is the resistance to breaking, chipping, or fracturing from impact. A diamond has only “good” but not “exceptional” toughness.
This reduced impact resistance is due to a structural characteristic known as cleavage. Cleavage refers to the tendency of a crystal to break along specific, weaker planes of atomic arrangement. Diamonds have four directions of perfect cleavage, meaning a sharp, forceful blow delivered in the right direction can cause the stone to split or chip, especially at vulnerable points like the girdle or pointed corners in certain cuts. This chipping or fracturing is the most common form of damage seen on diamond jewelry and is often mistakenly believed by the public to be a deep scratch.
Protecting Your Diamond Jewelry
Protecting a diamond involves mitigating the risks of both scratching and impact damage. Since diamond-on-diamond contact is the only way a stone will be scratched, it is important to store diamond jewelry separately from other pieces. Using individual fabric pouches or a jewelry box with separate compartments prevents stones from rubbing against one another and causing micro-abrasions.
To protect against chipping, it is prudent to remove diamond jewelry before engaging in high-impact activities, such as sports, gardening, or heavy labor, which carry the risk of a forceful blow. A sharp impact against a hard surface, like a metal door or a countertop, can exploit the diamond’s cleavage planes. Additionally, having the prongs and setting inspected by a jeweler at least once or twice a year ensures the stone is securely held, reducing its vulnerability to accidental impact and loss.