The simple answer to whether white gold is the same as pure gold is no. Pure gold, or elemental gold, is a naturally soft, yellow metal designated as 24-karat (24K). White gold is an alloy, a mixture created by combining pure gold with other metals to alter its color and enhance its physical properties. This fundamental difference establishes that white gold is a manufactured material distinct from its primary component.
The Composition of White Gold
The creation of white gold involves a precise metallurgical process to bleach the natural yellow color of pure gold. Since 24K gold is too soft for practical jewelry use, it is combined with harder metals to increase durability, which simultaneously changes the hue. White gold purity is measured by the karat system: 18K white gold is 75% pure gold, and 14K white gold is 58.3% pure gold, with the remainder being alloying metals.
To achieve a whitish tone, pure gold is mixed with white metals such as palladium, nickel, silver, or zinc. Palladium is a common alloy used in higher-end white gold due to its naturally white color, while nickel is a cost-effective option that provides significant strength. The specific combination of these metals determines the final characteristics of the alloy, including its hardness and malleability.
It is a common misconception that the alloy itself is a bright, true white. The underlying mixture of gold and white metals usually results in a color that is a pale, grayish-yellow, or dull brown. Gold-palladium alloys tend to be softer and more pliable, making them suitable for setting gemstones. Conversely, nickel-containing alloys are harder and more robust, making them ideal for items like rings that require higher resistance to bending.
Achieving the Bright White Finish
The brilliant, mirror-like white appearance associated with white gold is not inherent to the alloy. It is achieved through rhodium plating, a specialized industrial process. Rhodium is a highly reflective, silvery-white metal from the platinum family that is resistant to corrosion. This plating is applied as an extremely thin layer over the grayish-yellow gold alloy.
The process of electroplating involves meticulously cleaning the jewelry to remove all surface contaminants, ensuring the rhodium adheres properly. The piece is then submerged in a rhodium solution while an electric current is passed through it, causing rhodium ions to deposit onto the gold surface. This application masks the underlying alloy’s color and adds a layer of protection.
The thickness of the rhodium layer is typically very small, often measuring less than one micron. This thin coating provides the final product with its characteristic bright white luster and increases the item’s resistance to scratches. Without this coating, the jewelry would display the duller, slightly yellowish tone of the base alloy.
Comparing Durability, Value, and Maintenance
Differences in composition and finish significantly impact white gold’s durability and maintenance compared to pure or traditional yellow gold alloys. Since white gold is alloyed with harder metals like nickel and palladium, the resulting material is generally more durable and scratch-resistant than an equivalent karat of yellow gold. The rhodium plating also contributes to this initial hardness and resistance to wear.
The inherent monetary value of white gold is determined by the percentage of pure gold it contains, indicated by its karat rating. Therefore, a 14K white gold item has the same intrinsic gold value as a 14K yellow gold item of the same weight. The cost of rhodium plating or the use of palladium can make white gold slightly more expensive.
The most significant maintenance requirement for white gold is periodic re-plating. Over time, the thin rhodium layer wears away, especially on areas of high friction like the underside of a ring band. When this plating wears off, the underlying grayish-yellow color of the alloy becomes visible. Jewelers typically recommend re-plating the piece every one to three years to restore its brilliant white finish.
An additional consideration is the potential for skin reactions, as white gold alloys often contain nickel, a common allergen. For the approximately one in eight people with a nickel sensitivity, prolonged contact with the metal can cause a skin rash. The rhodium plating acts as a temporary barrier, but once it wears away, the nickel in the alloy can come into direct contact with the skin. Individuals with known allergies are often advised to seek out white gold made with palladium or choose platinum.