Diamond

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Diamond structure

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Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. At room temperature and pressure, another solid form of carbon known as graphite is the chemically stable form, but diamond almost never converts to it. Diamond has the highest hardness and thermal conductivity of any natural material, properties that are utilized in major industrial applications such as cutting and polishing tools. They are also the reason that diamond anvils can be used to create high-pressure environments.

Properties

Diamonds are renowned for their optical properties, which include a high refractive index and strong dispersion of light. These properties contribute to their brilliance and fire, making them highly sought after as gemstones in jewelry. The hardness of diamond is due to the strong covalent bonding between its atoms, and it is the hardest known natural material on the Mohs scale of mineral hardness.

Formation

Diamonds form under high-pressure, high-temperature conditions that exist only about 100 miles beneath the Earth's surface in the mantle. Most natural diamonds have ages between 1 billion and 3.5 billion years. They are brought close to the Earth's surface through deep-source volcanic eruptions by a magma, which cools into igneous rocks known as kimberlites and lamproites.

Industrial Uses

Due to their hardness, diamonds are used in cutting, grinding, and drilling. Industrial diamonds are embedded in large saw blades, drill bits, and grinding wheels. Specialized applications include the use of diamond anvils in high-pressure experiments and diamond windows in high-power lasers.

Gemstones

Diamonds are also valued as gemstones. The quality of a diamond is determined by the "four Cs": carat, cut, color, and clarity. The cut of a diamond greatly affects its brilliance and is a critical aspect of its overall appearance. The color of gem-quality diamonds ranges from completely colorless to yellow or brown, with colorless stones being the most valuable. Clarity refers to the presence of internal or external flaws, known as inclusions and blemishes, respectively.

Synthetic Diamonds

Synthetic diamonds can be produced by two main methods: High-pressure high-temperature (HPHT) and chemical vapor deposition (CVD). These diamonds have the same physical properties as natural diamonds and are used in both industrial applications and as gemstones.

Famous Diamonds

Some of the most famous diamonds include the Cullinan Diamond, the Hope Diamond, and the Koh-i-Noor. These diamonds have storied histories and are often associated with royalty and legend.

See Also

• Carbon
• Graphite
• Mohs scale of mineral hardness
• Kimberlite
• Lamproite
• Synthetic diamond
• Gemstone