A diamond is unequivocally considered a gemstone, meeting all the necessary criteria established in both the scientific and commercial worlds. Confusion often arises from the diamond’s unique status and its historical placement in a separate commercial category. Understanding that diamonds are gemstones is the starting point for recognizing how their distinct properties set them apart from other materials used for adornment.
Defining the Term Gemstone
A gemstone is broadly defined as a piece of mineral crystal, rock, or organic material that is cut and polished for use in jewelry or other human adornments. Classification relies on three fundamental qualities: beauty, durability, and rarity. Beauty encompasses aesthetic characteristics like color, clarity, and the ability to interact with light, often referred to as “fire” or brilliance.
Durability relates to a stone’s ability to resist wear and tear, including its hardness (resistance to scratching) and toughness (resistance to chipping and breaking). Rarity refers to the scarcity of the material in nature, which significantly influences its market value and desirability.
While most gemstones are inorganic minerals, the category also includes non-mineral materials. Examples include organic substances like pearl and amber, and rocks composed of multiple minerals, such as lapis lazuli.
Diamond’s Unique Properties and Composition
The diamond meets the criteria for a gemstone through its unique material science. It is an inorganic mineral composed of nearly pure carbon (typically about 99.95%). This carbon structure forms under extreme heat and pressure approximately 100 miles beneath the Earth’s surface, resulting in an isometric crystal lattice.
The atoms within this structure are held together by strong covalent bonds, linking each carbon atom to four neighbors. This tightly-bonded arrangement is responsible for the diamond’s unparalleled hardness, scoring a perfect 10 on the Mohs scale. This makes it the hardest known natural material, ensuring the stone’s durability and resistance to scratching.
The diamond’s beauty is derived from its optical properties, most notably its very high refractive index. This high refraction, combined with a high degree of dispersion, causes light entering the stone to break up into the spectrum of colors. This creates the characteristic “fire” or sparkle.
The Historical Classification of Precious Gems
Diamonds are often singled out due to a historical categorization that divided gemstones into “precious” and “semi-precious.” This distinction was never based on a scientific or formal gemological standard, but rather on historical scarcity and market value.
The four stones traditionally classified as “precious” are the diamond, ruby, sapphire, and emerald. These four gems were historically the rarest and most consistently valued, particularly before the discovery of large new deposits of other minerals. For example, amethyst was once considered precious until significant finds in Brazil decreased its rarity and value.
Modern gemology largely considers this traditional division outdated. Many so-called “semi-precious” stones, such as high-quality opal or tanzanite, can be significantly rarer and more valuable than a low-quality diamond. However, the historical momentum of the “precious” label ensures the diamond continues to hold a unique cultural and commercial status among all gemstones.