Karat

Karat, abbreviated as kt, is a unit of fineness used to describe the purity of gold in an alloy. It expresses the proportion of gold by weight in a total of 24 parts. Therefore, 24 karat gold is pure gold, while 18 karat, 14 karat, or 10 karat gold contain 18/24, 14/24, or 10/24 gold respectively and the remainder consists of other metals such as silver, copper, nickel, or zinc. In jewelry, karat is commonly used to indicate color and hardness, with higher karat values yielding a richer yellow color and softer metal.

In addition to karat, the term carat is used in different contexts. For gemstones, carat (with a c) is the metric unit of mass equal to 200 milligrams. This is distinct from karat, which measures gold fineness. The two terms are often confused because they share a common historical root, but they denote different properties.

Common gold karat values include 24K (pure gold), 18K (75% gold), 14K (approximately 58.3% gold), and 10K (41.7% gold). Lower karats are harder and more durable due to the alloying metals, while higher karats are more malleable and prone to scratching and bending. Jewelry is typically stamped with marks such as “24K,” “18K,” “750” (for 18K), “585” (for 14K), or “417” (for 10K) to indicate fineness. The actual appearance and properties depend on the alloy composition as well as the presence of other metals, which can also produce yellow, white, or rose hues.