18 karat gold means that the alloy contains 18 parts gold out of 24 parts, or 75% gold. The remaining 25% is made up of other metals, such as copper, silver, zinc, or nickel. These metals are added to alter the color, hardness, and other properties of the gold alloy.
18 karat gold is commonly used in jewelry, as it offers a good balance between the rich color of gold and its durability. However, it is still softer than pure gold, so it is not suitable for items that will be subjected to rough wear and tear.
Other common gold karatages include 10 karat (41.7% gold), 14 karat (58.3% gold), and 22 karat (91.7% gold). The higher the karatage, the higher the gold purity and the softer the alloy.
