Karat vs. Carat: Understanding the Difference Karat" and "Carat" may sound similar, but they refer to different properties in jewelry. Karat (K) measures the purity of gold, with 24K being pure gold. On the other hand, Carat (ct) is a unit of weight used for gemstones like diamonds, with one carat equaling 200 milligrams. Understanding this distinction is crucial when buying jewelry, as the karat affects gold’s durability, while the carat determines the size and value of gemstones. Make informed choices by knowing the difference!