Karats

Karats, in the context of gold, refer to a unit of fineness used to express the proportion of gold in an alloy. The term is spelled with a k to distinguish it from carat, the unit used for measuring gemstone weight. In this system, 24 karat gold is considered pure gold by mass, with other karat values indicating a specific fraction of gold blended with other metals such as copper, silver, or nickel.

Common values include 22K (approximately 91.7% gold), 18K (75% gold), 14K (58.3% gold), and 10K (41.7% gold). As karat value decreases, more alloying metals are added, changing not only the gold content but also properties such as color, hardness, and durability. Higher karat gold typically appears richer in color and is softer and more prone to scratching and denting, while lower karat gold tends to be harder and more suitable for everyday wear.

The karat system is distinct from the gemstone carat, which measures weight (with 1 carat equaling 0.2 grams). Gold karats are determined by assaying methods that estimate gold content, including fire assay and X-ray fluorescence. The term is widely used in jewelry markets and hallmarking, with kt or karat listed on pieces to denote fineness.

In summary, karats express the gold purity of an alloy, influencing appearance and durability, and should not be confused with carats, the unit of gemstone weight.