karat

This term serves as a specialized technical measurement specifically for the purity of gold. It operates on a scale of 24, where the number indicates how many parts of gold are present in 24 total parts of the alloy. It is distinct from the word carat, which refers to the weight of gemstones, although the two are frequently confused in casual speech.

Because it is a unit of measurement, it functions as a countable noun. It is typically used in the context of jewelry appraisal, metallurgy, and luxury commerce to denote value and quality.