Important Differences Between Diamond and Graphite


Diamond is a naturally occurring, crystalline form of carbon renowned for its exceptional hardness and dazzling brilliance. It is composed of carbon atoms arranged in a strong, three-dimensional lattice structure through covalent bonding. Each carbon atom forms four strong covalent bonds with its neighboring atoms, resulting in a rigid network. This structure grants diamond its remarkable properties, making it the hardest known natural material. Diamonds are typically transparent with a range of colors, but they can also appear in various shades. They are coveted for their use in jewelry and are also utilized in cutting tools, industrial applications, and as a symbol of enduring love and luxury.

Physical Properties of Diamond:

  • Hardness:

Diamond is the hardest natural material known, scoring a 10 on the Mohs scale of mineral hardness.

  • Luster:

It has a high refractive index, giving it a brilliant, glassy luster.

  • Transparency:

Diamonds are typically transparent, but they can also be translucent or opaque, depending on impurities or inclusions.

  • Color:

Diamonds can be colorless, but they also occur in various shades including yellow, brown, and rarely in other colors like blue, green, or pink due to impurities.

  • Density:

Diamond has a high density, with a specific gravity of approximately 3.5.

  • Crystal Structure:

It has a crystalline structure with a face-centered cubic lattice, where each carbon atom forms four strong covalent bonds with neighboring atoms.

  • Refractive Index:

It has a high refractive index, meaning it can bend and reflect light at a greater angle than many other substances.

Chemical Properties of Diamond:

  • Composition:

Diamond is composed of carbon atoms arranged in a three-dimensional crystal lattice.

  • Combustibility:

Diamond is not easily combustible and requires extremely high temperatures and oxygen levels to burn.

  • Insolubility:

It is insoluble in water and most acids, showcasing high chemical stability.

  • Resistance to Corrosion:

Diamond is highly resistant to chemical corrosion or reaction with acids and bases.

  • Thermal Conductivity:

It is an excellent conductor of heat due to its strong carbon-carbon bonds.

  • Electrical Conductivity:

Pure diamond is an electrical insulator, but it can conduct electricity when doped with certain impurities.

  • Reaction with Oxygen:

Diamond can react with oxygen at very high temperatures, forming carbon dioxide.

Uses of Diamond in real-life

  • Jewelry:

Diamonds are most famously used in jewelry, including engagement rings, necklaces, earrings, and other ornamental pieces.

  • Cutting Tools:

Industrial-grade diamonds are used in cutting, grinding, and drilling tools for their unmatched hardness.

  • Abrasives:

Diamonds are used in abrasive materials for cutting and polishing hard surfaces, like metals and stones.

  • Electronics:

Synthetic diamonds with specific properties are used in high-performance electronics, including semiconductors, transistors, and laser diodes.

  • Medical Tools:

Diamond-coated surgical instruments and saws are used in specialized medical procedures.

  • Heat Sink Materials:

Due to its excellent thermal conductivity, diamonds are used in heat sinks for electronic devices.

  • Oil and Gas Drilling:

Diamonds are used in drill bits for oil and gas exploration due to their ability to cut through extremely hard materials.

  • Scientific Research:

Diamonds are used in high-pressure experiments and as windows for transmitting infrared radiation.

  • Laser Technology:

Diamonds are used as laser windows and in the production of laser diodes.

  • Speaker Domes:

Synthetic diamonds are used in high-end speakers for their ability to transmit sound with minimal distortion.

  • Watchmaking:

Diamonds are used as bearings and for precision movements in high-end watches.

  • Water Treatment:

Diamond-coated electrodes are used in water treatment plants for electrochemical processes.

  • Protective Coatings:

Diamonds are used as protective coatings on tools and equipment to increase wear resistance.

  • Dental Tools:

Diamond-coated dental burs and instruments are used for precise dental procedures.

  • Gemological Tools:

Diamonds are used as reference points in the grading and identification of other gemstones.


Graphite is a naturally occurring form of crystalline carbon known for its unique properties. It is composed of carbon atoms arranged in closely packed, parallel layers within a three-dimensional crystal lattice. These layers are loosely held together by weak van der Waals forces, allowing them to easily slide over each other. This structure imparts graphite with its characteristic slippery feel and lubricating properties. Unlike diamond, graphite is relatively soft and is used as a solid lubricant. It is opaque and has a dark grey to black color. Graphite is an excellent conductor of electricity due to the presence of free electrons within its layers. It finds diverse applications in lubricants, electrodes, batteries, refractories, and as a crucial component in the production of graphene.

Physical Properties of Graphite:

  • Appearance:

Graphite is a dark grey to black, opaque substance.

  • Crystal Structure:

It has a hexagonal crystal lattice structure, where carbon atoms are arranged in flat, closely packed layers.

  • Lubricating Properties:

Due to its slippery feel and weak inter-layer bonding, graphite acts as a solid lubricant.

  • Conductivity:

Graphite is an excellent conductor of electricity due to the presence of free electrons that can move within its layers.

  • Density:

It has a relatively low density of around 2.2 – 2.3 grams per cubic centimeter.

  • Melting Point:

Graphite has a very high melting point of about 3,700 degrees Celsius (6,732 degrees Fahrenheit).

  • Hardness:

Despite being soft in comparison to diamond, graphite is still relatively hard and is used as a refractory material.

Chemical Properties of Graphite:

  • Composition:

Graphite is composed entirely of carbon atoms.

  • Stability:

It is chemically stable and does not react with most chemicals, including acids and bases, at room temperature.

  • Combustibility:

Graphite is non-combustible under normal conditions.

  • Oxidation Resistance:

It is resistant to oxidation at room temperature, but can slowly oxidize at high temperatures in the presence of oxygen.

  • Reactivity with Other Elements:

Graphite does not readily react with other elements, making it a stable and unreactive material.

  • Insolubility:

It is insoluble in water and most organic solvents.

  • Thermal Conductivity:

Graphite is an excellent conductor of heat, which makes it suitable for various high-temperature applications.

  • Exfoliation:

Graphite can be mechanically exfoliated to produce individual layers known as graphene.

Uses of Graphite in real-life

  • Pencils:

Graphite is a primary component in the “lead” of pencils, allowing for smooth and consistent writing.

  • Lubricants:

Its slippery nature and weak inter-layer bonding make graphite an excellent solid lubricant in applications like machinery, locks, and automotive parts.

  • Electrodes:

High-quality graphite is used in electrical applications, such as electrodes in electric arc furnaces and in the production of batteries.

  • Refractories:

Graphite’s high melting point and chemical stability make it suitable for use in refractory materials used in high-temperature applications like foundries and metalworking.

  • Heat Shields:

It is used in aerospace applications for heat shields and as a thermal insulator.

  • Nuclear Reactors:

Graphite is used as a moderator in nuclear reactors to slow down neutrons and control the nuclear fission process.

  • Fuel Cells:

It is used as a component in the electrodes of certain types of fuel cells.

  • Foundry Facings:

Graphite is used as a facing material in foundry molds to improve the surface finish of castings.

  • Brake Linings:

Graphite is used in brake linings and clutches due to its heat resistance and low wear characteristics.

  • Gaskets and Seals:

It is used in gaskets and seals for its ability to withstand high temperatures and pressures.

  • Graphene Production:

Graphite serves as a precursor for the production of graphene, a highly sought-after material for various advanced applications.

  • Nanotechnology:

Graphite is used as a starting material for the production of carbon nanotubes and other nanostructured materials.

  • Electrolytic Cells:

It is used in electrolytic cells for its electrical conductivity and resistance to chemical reactions.

  • Golf Clubs and Tennis Rackets:

Graphite composites are used in the construction of sporting equipment for their lightweight and strength properties.

Important Differences Between Diamond and Graphite

Basis of Comparison Diamond Graphite
Crystal Structure Tetrahedral arrangement of carbon Hexagonal layers of carbon
Hardness Hardest natural material (Mohs 10) Relatively soft (Mohs 1-2)
Conductivity Insulator of electricity Excellent electrical conductor
Appearance Transparent, colorless or colored Opaque, dark grey to black
Bonding Type Strong covalent bonds within a crystal Weak van der Waals forces between layers
Lubrication Not a good lubricant Excellent solid lubricant
Density High density (around 3.5 g/cm³) Relatively low density (around 2.2 g/cm³)
Cleavage Perfect cleavage along crystal faces No distinct cleavage
Industrial Applications Cutting tools, jewelry, abrasives Lubricants, electrodes, refractories
Electrical Applications Limited use in electronics Used in electrical components
Melting Point Very high (around 3,700°C) Sublimates at high temperatures
Thermal Conductivity Low thermal conductivity High thermal conductivity
Reactivity with Oxygen Resistant to oxidation at any temperature Can oxidize at high temperatures
Chemical Stability Highly chemically stable Chemically stable at room temperature
Occurrence Relatively rare and natural Abundant and found naturally

Important Similarities Between Diamond and Graphite

  • Composition:

Both diamond and graphite are composed entirely of carbon atoms.

  • Allotropes:

They are both allotropes of carbon, meaning they are different structural forms of the same element.

  • Natural Occurrence:

Both diamond and graphite are naturally occurring minerals found in the Earth’s crust.

  • Carbon Bonds:

In both diamond and graphite, carbon atoms form strong covalent bonds with other carbon atoms.

  • Chemical Stability:

They are both chemically stable and do not readily react with most chemicals at room temperature.

  • Insolubility:

Both substances are insoluble in water and most common solvents.

  • High Melting Points:

They both have very high melting points, with diamond having an exceptionally high melting point.

  • Carbon Allotropy:

Both diamond and graphite demonstrate the remarkable diversity of properties that carbon can exhibit in different atomic arrangements.

  • Electrical Conductivity (in specific cases):

While diamond is an electrical insulator, both diamond and graphite can conduct electricity when doped with specific impurities.

  • Reactivity with Oxygen (at high temperatures):

Both diamond and graphite can react with oxygen at very high temperatures, leading to their conversion to carbon dioxide.

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