Diamonds are so hard because of their crystalline structure. Each carbon atom inside a diamond is bonded to four other carbon atoms in a very rigid way, giving the diamond its exceptional strength.
Diamonds are made up solely of carbon atoms bonded together in a very particular way. Each atom is surrounded by four other atoms in a tetrahedral shape, much like a triangular-based pyramid. This very regular organization, spread throughout its structure, forms an ultra-strong crystalline lattice that is difficult to break or deform. It is precisely this dense and hyper-ordered atomic organization that accounts for much of the strength and hardness of diamonds.
In a diamond, each carbon atom is bonded to four other neighboring atoms by super strong covalent bonds. These bonds are like each atom deciding to share electrons with its neighboring buddies, thus linking everyone together in a hyper stable and resistant way. A regular three-dimensional network is then formed with these ultra-strong connections, making the whole structure almost impossible to break. This particular type of bonding largely explains why diamonds are so hard and robust against scratches or shocks.
The exceptional hardness of diamond primarily comes from its atomic structure. Imagine a kind of ultra-tight mesh, where each carbon atom forms very strong bonds with four other neighboring atoms: it is this dense network that makes diamond so tough. These bonds, called covalent, are extremely strong and require enormous energy to be broken. As a result, practically no natural mineral can scratch or mark a diamond. On the scale of mineral hardness, known as the Mohs scale, diamond reaches the maximum value of 10, far ahead of other common materials. But be careful, don’t confuse hardness with shock resistance: a diamond can certainly scratch almost everything it encounters, but it can break under a violent blow due to its crystalline structure.
Diamonds are primarily formed in an extreme environment: very high pressure (up to about 150 kilometers beneath the Earth's surface) and crazy temperatures (over 1000 degrees Celsius). These extreme conditions push carbon atoms to tightly pack together, creating very strong bonds between them. The higher the pressure and temperature, the more efficiently the atoms organize: the result is an ultra-rigid and resilient structure. It is precisely this formation under extreme conditions that explains why natural diamonds are significantly harder than most minerals found on the surface.
The diamond is the uncontested champion in terms of hardness, far ahead of other known minerals. Take quartz, for example, which is found everywhere in sand: it easily scratches glass but cannot withstand a diamond. The same goes for corundum, the mineral that gives us sapphires and rubies: very strong, but still a step behind the diamond. In fact, on the Mohs scale (which measures hardness by ranking minerals from 1 to 10), only diamond achieves the maximum score of 10. Its particular atomic structure and very strong covalent bonds explain this remarkable difference from other minerals.
The word 'diamond' comes from the Greek word 'adamas', which means 'invincible' or 'indestructible', a nod to the impressive resistance of this mineral.
Although diamonds are composed solely of carbon atoms, they have a very different structure from that of graphite (the tip of your pencil), which explains why graphite is brittle while diamond is extremely hard.
Despite their exceptional hardness, diamonds can be broken by violent impacts because their perfect atomic structure also makes them relatively fragile in the face of strong and sudden shocks.
Diamond is so hard that it is used industrially to cut, polish, or drill other very tough materials like glass, ceramics, or even stone itself.
The hardness of diamond is generally measured using the Mohs scale, which ranks minerals based on their ability to scratch one another. Diamond receives the maximum value of 10 on this scale. In the laboratory, other more precise techniques such as Vickers or Knoop tests can also be used.
The diamond is the hardest known natural mineral to date. However, some synthetic materials, such as nanocrystalline diamond aggregate or certain special ceramics produced in laboratories, have hardness that is equivalent to or even greater than that of natural diamond.
Synthetic diamonds, despite having a chemical composition and properties that are nearly identical to natural diamonds, are generally less expensive because the laboratory manufacturing process is less costly and quicker, while also avoiding the challenges associated with mining extraction.
Yes, despite its exceptional hardness, a diamond can be broken or chipped under a violent shock in a certain crystallographic direction known as the cleavage plane. It can also be scratched only by another diamond.
The significant difference in hardness between graphite and diamond comes from the way their carbon atoms are arranged. In diamond, the atoms are assembled in a compact three-dimensional network with strong covalent bonds, which makes its crystal extremely hard. In contrast, in graphite, the carbon atoms are arranged in stacked layers that are connected to each other by weak interactions, making its structure much less resistant.
0% of respondents passed this quiz completely!
Question 1/5
