What is the Difference Between Silicon Dioxide and Diamond

The main difference between silicon dioxide and diamond is that silicon dioxide is a compound composed of silicon and oxygen atoms, whereas diamond is composed solely of carbon atoms.

Both silicon dioxide and diamond are naturally occurring minerals. Both have organized, lattice-like structures and thus share some similarities. However, these two minerals also have various differences, which make them useful in different industries.

Key Areas Covered

1. What is Silicon Dioxide 
      – Definition, Features, Applications
2. What is a Diamond
      – Definition, Features, Applications 
3. Similarities Between Silicon Dioxide and Diamond
      – Outline of Common Features
4. Difference Between Silicon Dioxide and Diamond
      – Comparison of Key Differences
5. FAQ: Silicon Dioxide and Diamond
      – Frequently Asked Questions

Key Terms

Silicon Dioxide, Diamond

Difference Between Silicon Dioxide and Diamond - Comparison Summary

What is Silicon Dioxide

Silicon dioxide is a chemical compound composed of silicon and oxygen atoms. It exists in various crystalline and amorphous forms and exhibits a wide range of physical and chemical properties. Silicon dioxide can exist in different crystalline structures, with quartz and cristobalite being two of the most common forms. These structures are characterized by a three-dimensional arrangement of silicon and oxygen atoms in a tetrahedral configuration. Silicon dioxide is known for its high hardness. Quartz, in particular, ranks 7 on the Mohs scale of mineral hardness, making it more durable than most common minerals. Silicon dioxide has a high melting point of around 1,710 degrees Celsius (3,110 degrees Fahrenheit). This property makes it suitable for applications where high-temperature stability is required. Crystalline silicon dioxide, such as quartz, is transparent to visible light. This transparency makes it valuable for optical applications, including the production of lenses and prisms.

Silicon Dioxide vs Diamond

Figure 1: Chemical Structure of Silicon Dioxide

Silicon dioxide, due to its versatile properties, finds widespread applications in various industries. It is crucial in electronics and semiconductors, serving as an insulating material and gate dielectric in ICs and MOSFETs. Crystalline silicon dioxide, like quartz, is used in optics for creating lenses, prisms, and windows with excellent transparency to visible and ultraviolet light. In glass production, amorphous silica is a key component, forming everything from containers and windows to optical fibers. Crystalline forms of silicon dioxide, such as cristobalite and tridymite, are utilized in ceramics and refractories for their high-temperature stability. It also plays a role as a desiccant in diverse applications and as a proppant in hydraulic fracturing in the oil and gas industry. Silica compounds are also found in cosmetics, personal care products, chemical containers, and pharmaceuticals, performing various functions in these applications.

What is Diamond

Diamond is one of the most precious and sought-after gemstones on Earth. Diamonds form deep within the Earth under intense pressure and heat. They take millions and billions of years to form. What makes a diamond stand out is its crystal structure, where carbon atoms are packed in a strong lattice. This arrangement is why diamond is the hardest natural material on Earth. That’s what gives it its toughness, making it perfect for engagement rings that last a lifetime. Besides its durability, the diamond’s clarity and the way it bends light to create those sparkles of color are truly one-of-a-kind.

Compare Silicon Dioxide and Diamond

Figure 2: Diamond

In terms of hardness, diamonds rank at the top of the scale with a score of 10, making them incredibly resistant to scratching and wear. Additionally, it’s an excellent conductor of heat, making it useful in various industrial applications, like cutting and grinding tools. The brilliance and fire you see in diamonds are due to their ability to disperse light in a unique and captivating way.

Diamonds have diverse applications in various fields. They are commonly used in jewelry, such as engagement rings and ornamental pieces, thanks to their beauty and durability. In industries, their hardness makes them ideal for tools like cutting instruments and drill bits. Diamonds are also essential in technology, particularly in semiconductors, thanks to their thermal conductivity and durability. They serve as windows for high-pressure equipment and optical components in lasers. In scientific research, diamonds play a vital role in high-pressure experiments, enabling the study of materials under extreme conditions.

Similarities Between Silicon Dioxide and Diamond

  • Silicon dioxide exists in various crystalline forms, and diamond also has a crystalline form.
  • Silicon dioxide and diamonds are known for their hardness.
  • Certain forms of silicon dioxide and diamond are transparent to visible light.
  • Both have high melting points when compared to other substances.

Difference Between Silicon Dioxide and Diamond


Silicon dioxide is a mineral consisting of silicon and oxygen atoms in a 1:2 ratio, while diamond is a mineral composed solely of carbon atoms.


Silicon dioxide can exist in various crystalline and amorphous forms, while diamond has a unique three-dimensional tetrahedral crystal lattice structure where each carbon atom forms strong covalent bonds with four other carbon atoms.


Moreover, silicon dioxide, depending on its form, can vary in hardness but generally ranks at 7 on the Mohs scale. Diamond, in contrast, is exceptionally hard, ranking at a perfect 10 on the Mohs scale.


Silicon dioxide is abundant in nature and found in various forms, including sand, glass, and quartz, while diamond is relatively rare and precious.

Electrical Conductivity

Silicon dioxide can serve as an insulator or semiconductor, depending on its form, whereas diamond is a poor electrical conductor due to its covalent bonding.

Melting Point

Silicon dioxide has a relatively lower melting point, around 1,710°C (3,110°F), compared to diamond, which has a high melting point, exceeding 3,800°C (6,872°F).

FAQ: Silicon Dioxide and Diamond

Why is silicon dioxide not as strong as diamond?

Silicon dioxide is not as strong as diamond because its atomic structure is different. In diamond, the carbon-carbon (C-C) bonds are incredibly strong, forming a tightly bonded lattice, whereas in silicon dioxide, the silicon-silicon (Si-Si) bonds are not as strong.

How is diamond similar to silicon dioxide?

Both diamond and silicon dioxide have organized, lattice-like structures. Both are comparatively hard and have high melting points. Moreover, in certain forms, both diamond and silicon dioxide are transparent to visible and ultraviolet light.

Why is silicon similar to diamond?

Silicon shares some similarities with diamond due to its crystalline structure and atomic composition. Both silicon and diamond are composed of a lattice structure formed by covalent bonds between their constituent atoms.


Silicon dioxide is a compound composed of silicon and oxygen atoms, whereas diamond is composed solely of carbon atoms. Diamond has a higher melting point and is harder than silicon dioxide. This is the main difference between silicon dioxide and diamond.


1. “Diamond.” Wikipedia. Wikipedia Foundation.
2. “Silicon dioxide.” Wikipedia. Wikipedia Foundation.

Image Courtesy:

1. “Silicon dioxide-2D-dimensions” By Grasso Luigi – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “Diamond 4” By Géry PARENT – Own work (Public Domain) via Commons Wikimedia

About the Author: Hasini A

Hasini is a graduate of Applied Science with a strong background in forestry, environmental science, chemistry, and management science. She is an amateur photographer with a keen interest in exploring the wonders of nature and science.

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