diamonds

Diamonds are a crystalline form of carbon in which atoms are arranged in a diamond cubic lattice. The strong covalent bonds throughout this lattice give exceptional hardness, rating 10 on the Mohs scale. Diamonds have a high refractive index (~2.42) and high dispersion, producing the characteristic sparkle or "fire" seen in well-cut stones. They also conduct heat very efficiently, making them useful in heat-intensive industrial applications. Natural diamonds range in color from colorless to yellow to brown, with rare gray, red, pink, blue, and green varieties.

Natural formation occurs under high pressure and high temperature deep within Earth's mantle, followed by transport to the surface through volcanic eruptions that form kimberlite pipes. Erosion can release diamonds into riverbeds and alluvial deposits. Most mined diamonds are used in jewelry, while a smaller share serves industrial purposes such as cutting, grinding, and polishing.

In addition to natural diamonds, synthetic diamonds are produced commercially by high-pressure, high-temperature (HPHT) or chemical vapor deposition (CVD) methods. Synthetic diamonds can closely resemble natural ones and are used for jewelry and industrial tools. Impurities such as nitrogen or boron influence color, giving yellow, brown, blue, or other hues; some colors arise from lattice defects.

Quality evaluation focuses on cut, color, clarity, and carat weight. Grading laboratories provide certificates that describe a stone’s characteristics. Ethical concerns about conflict diamonds have led to the Kimberley Process, an international certification scheme, though enforcement remains imperfect. Care and maintenance include gentle cleaning and avoiding harsh chemicals; proper storage minimizes scratching and damage.