Aside from never using the item, it is nearly impossible to prevent some white gold pieces from turning yellow. This is particularly true for jewelry. White gold jewelry, especially rings, has a tendency to gradually turn yellow due to natural erosion caused by friction and normal wear and tear.
White gold is composed of yellow gold mixed with other metal alloys such silver, nickel, palladium and manganese. These alloys are added to yellow gold in order to strengthen it for jewelry making. The white color is achieved by dipping the original composite gold into a plating mixture made from rhodium. It is this rhodium finish that is popularly known as white gold. However, rhodium plating has an average longevity of around three to five years. After that, the plating begins to fade in areas, exposing the original yellow tinged gold underneath.
Yellowing tends to affect rings more than other jewelry pieces. For instance, white gold earrings often maintain their coloring indefinitely. Alternatively, a white gold ring is more likely to lose its white finish after constant exposure to surfaces, or friction caused by it being rubbed against skin. Jewelry and other white gold items can be dipped again in rhodium plating, thus, restoring their original shiny finish.