Facet

Facet has several related meanings in science, technology, and language. Broadly, a facet is a flat surface that forms part of a geometric object or a particular aspect of something viewed as a whole.

In geometry, a facet is a flat polygonal face of a polyhedron or higher‑dimensional polytope. The surface of a polyhedron is made up of its facets, and the arrangement of these facets determines the figure’s shape. For example, a cube has six square facets.

In crystallography and mineralogy, a facet refers to a natural plane on a crystal produced by cleavage or fracture. These cleavage planes influence the crystal’s shape, its growth habits, and how minerals are identified. Gemstones, including diamonds, are often described by the number and arrangement of facets on their cut surfaces, which are designed to maximize light return.

In gemstone cutting, facets are the deliberately cut and polished surfaces that reflect and refract light. A classic modern diamond commonly has 57 or 58 facets arranged to enhance brilliance and fire.

Metaphorically, facet can mean an aspect or dimension of a complex thing, such as the different facets of a problem or a person’s multifaceted character. This usage emphasizes viewing a subject from multiple angles.

In human anatomy, facet joints are the small joints between the vertebrae in the spine. They guide motion and provide stability, but can be a source of pain when they deteriorate or become inflamed.

In information technology, facets are attribute-based categories used in faceted search and navigation, allowing users to filter results by multiple properties. This approach supports precise retrieval in large datasets.