Diamond

Hardness: 10 (Mohs scale), the hardest known natural material. Color: Pure diamonds are colorless, but impurities can lead to yellow, brown, blue, green, pink, red, orange, and black. Luster: Adamantine (brilliant, sparkly). Crystal Structure: Isometric (cubic), often forming octahedrons, modified cubes, or dodecahedrons. Cleavage: Perfect in four directions (octahedral). Specific Gravity: 3.51.

Formation Process: Diamonds typically form in two main ways: deep within the Earth's mantle (over 99% of natural diamonds) at pressures of 45-60 kilobars and temperatures of 900-1,300 degrees Celsius, then brought to the surface through deep-source volcanic eruptions (kimberlite and lamproite pipes); or through meteorite impacts where tremendous pressure and heat can transform carbon into diamond. Geological Age: Most natural diamonds are 1 to 3.3 billion years old.

Industry: Abrasives (cutting, grinding, drilling tools, polishing), optical windows, heat sinks in electronics. Jewelry: The most popular and valuable gemstone for rings, necklaces, bracelets, and earrings. Construction: Diamond-tipped tools for concrete cutting and drilling.

Diamonds are the only gemstone composed of a single element (carbon) and are the hardest known natural substance. They form under conditions of extreme heat and pressure, typically 90 to 120 miles below the Earth's surface. The largest uncut diamond ever found is the Cullinan Diamond (3,106.75 carats). Lab-grown diamonds are chemically, physically, and optically identical to natural diamonds.

Identification in the Field: While rarely found as loose specimens on the surface, larger, lower-quality diamonds (bort, carbonado) can be identified by their extreme hardness (scratches all other minerals), high specific gravity, and adamantine luster. In jewelry, they are identified by their brilliance and fire (dispersion of light into spectral colors). Common Locations Found: Major deposits are in Russia, Botswana, Democratic Republic of Congo, Australia, Canada, South Africa, and Angola. Tips for Collectors: Natural rough diamonds are often dull and greasy-looking before cutting and polishing. Look for octahedral shapes. Authenticity should always be verified by an expert using specialized equipment due to the presence of simulants and lab-grown diamonds.