Diamond is widely celebrated as the hardest natural substance on Earth, a reputation that originates from its unique atomic arrangement. The structure is composed entirely of pure carbon atoms, each one strongly bonded to four neighbors in a dense, three-dimensional tetrahedral lattice. This network of strong covalent bonds grants the material exceptional resistance to scratching and abrasion. Despite this incredible atomic strength, the commonly held belief that diamonds are completely indestructible is not accurate. Specific physical forces, chemical reactions, and controlled structural changes can all effectively destroy a diamond.
The Limits of Mechanical Force
The misconception of the diamond’s invincibility often arises from confusing two distinct properties: hardness and toughness. Hardness refers to a material’s resistance to being scratched, where diamond ranks a perfect 10 on the Mohs scale. Toughness, however, describes a material’s ability to resist breaking, chipping, or fracturing when subjected to a sharp, forceful impact. While diamond possesses supreme hardness, its toughness is only moderate compared to many other materials.
This difference in properties means that a diamond can be easily broken with a well-placed strike, even though it cannot be scratched by almost anything. The diamond’s crystalline structure contains specific directional weaknesses known as cleavage planes. These are four distinct planes within the crystal lattice where the carbon-carbon bonds are slightly weaker than in other directions.
If a sharp, sudden blow is applied precisely parallel to one of these cleavage planes, the energy of the impact can overcome the weaker bonds, causing the stone to split cleanly or shatter. Historically, diamond cutters have exploited this precise vulnerability, using a process called cleaving to split large rough diamonds with a single, accurate tap. This physical method results in the stone’s destruction not by crushing it, but by exploiting an inherent structural flaw under the right conditions.
Chemical Destruction Through Oxidation
The only truly definitive method for eliminating a diamond entirely is through chemical destruction, effectively vaporizing the material. Since a diamond is composed of pure carbon, it will undergo combustion if exposed to sufficient heat and oxygen. This process is an oxidation reaction, where the carbon atoms in the diamond react with the surrounding oxygen gas (\(\text{O}_2\)) to form carbon dioxide gas (\(\text{CO}_2\)).
The temperature required for this reaction to begin depends heavily on the concentration of oxygen present. In a pure oxygen environment, a diamond’s ignition point ranges from approximately \(690^\circ\text{C}\) to \(840^\circ\text{C}\) (\(1274^\circ\text{F}\) to \(1544^\circ\text{F}\)). Once this temperature is reached, the reaction becomes self-sustaining and the diamond will continue to burn with a pale blue flame until it is completely consumed.
If the combustion occurs in ordinary air, where oxygen is diluted with nitrogen, the temperature requirement is higher, around \(900^\circ\text{C}\) (\(1650^\circ\text{F}\)). In this less oxygen-rich environment, the heat source must be maintained constantly to continue the reaction. The final outcome of this process is the complete conversion of the solid carbon into an invisible gas, leaving behind no ash or residue if the original stone was pure.
Altering the Carbon Structure
Another method of destroying a diamond involves a polymorphic phase transition, which changes the material’s internal structure without a chemical reaction. Diamond is actually a metastable form of carbon at normal atmospheric pressure and room temperature, while the most thermodynamically stable form is graphite.
If a diamond is subjected to high temperatures in a vacuum or an inert environment—meaning oxygen is completely excluded—the carbon atoms will begin to rearrange. When the temperature exceeds approximately \(1700^\circ\text{C}\) (\(3092^\circ\text{F}\)) at ambient pressure, the dense tetrahedral lattice of the diamond breaks down. The atoms shift into the more stable, layered structure characteristic of graphite, converting the diamond into a different material with vastly changed physical properties. The resulting substance is a soft, black, opaque form of carbon that looks nothing like the original gemstone.