Spiegelglad

Spiegelglad is a German adjective used in technical language to describe surfaces that are mirror-smooth and highly reflective. The term is formed from spiegel, meaning "mirror," and glatt, meaning "smooth." In German-language texts, spiegelglad surfaces are associated with an extreme degree of polish, where the surface texture is nearly invisible and light reflects with minimal scattering.

In practice, spiegelglad surfaces occur in fields such as metallurgy, glassmaking, crystallography, and materials science, as well as in geology when describing polished sections of rocks or minerals. The designation emphasizes optical quality and a finish that approaches a perfect mirror.

Spiegelglad is less common in everyday language than spiegelglatt; in specialized contexts the terms may be used interchangeably or spiegelglad may appear in older or regional texts. In translations, spiegelglad is typically rendered as "mirror-smooth" or "mirror-polished."

Related concepts include spiegelglatt, the more common everyday equivalent, and the broader idea of a mirror finish. Surface finishing techniques such as polishing, lapping, and grinding are often employed to achieve spiegelglad-quality surfaces.