Karat (K) is a measure of the purity of gold. Pure gold is considered 24K, meaning 24 out of 24 parts are gold. The purity can be calculated using the formula:
Gold \space Purity = (\frac{Karat}{24}) \times 100Therefore, 22K gold contains about 91.6% gold, 18K contains 75% gold, 14K contains about 58.5%, and 24K gold is approximately 99.9% pure. The remaining portion consists of other metals added to improve strength and durability.
Carat (ct), in modern jewellery terminology, is generally used to measure the weight of gemstones such as diamonds, rubies and sapphires. One carat equals 200 milligrams or 0.2 gram. Thus, a 2-carat diamond weighs 0.4 gram. For example, a ring may have 18K gold with a 1-carat diamond: 18K indicates the purity of the gold, while 1 carat indicates the weight of the diamond.
