White gold is not a naturally occurring element, but rather a manufactured mixture of pure gold and other metals, known as an alloy. This process is necessary because pure gold, which is naturally yellow, is too soft and malleable to be used for durable jewelry. The amount of actual gold within any piece is determined solely by its karat mark, not its color. Pure gold is designated as 24-karat (24K), signifying 100% purity. White gold, like yellow and rose gold, is simply an alternative color created by adding specific other metals to the pure gold.
Decoding the Karat System
The percentage of gold in white gold is precisely defined by the karat system, which measures purity on a scale of 24 parts. To determine the gold content, the karat number is divided by 24, and the result is the percentage of pure gold present in the alloy. For instance, 18-karat (18K) gold contains 18 parts gold out of 24, resulting in a composition that is exactly 75% pure gold. This means an 18K white gold ring contains the same amount of gold as an 18K yellow or rose gold ring.
The most common purity levels for white gold jewelry are 14K and 18K, though 10K is also available. A 14K white gold piece is composed of 14 parts gold and 10 parts alloy, making it 58.3% pure gold. Conversely, 10K gold represents the lowest legal standard in some regions, containing 10 parts gold and 14 parts alloy, which is 41.7% pure gold. The decision between karats is a balance between purity and durability, as the higher the gold content, the softer the final metal becomes.
The three-digit number stamped on jewelry, such as 750 for 18K, 585 for 14K, and 417 for 10K, is an alternative way to express the exact gold content by parts per thousand. Understanding this quantitative breakdown clarifies that the color of the metal is a result of the other components in the mix. The percentage of non-gold metal, which is responsible for the white color and added strength, accounts for the remaining portion of the alloy.
The Metals That Make It White
The remaining percentage of the alloy consists of white metals that serve two primary functions: bleaching the gold’s natural yellow hue and increasing the overall strength of the metal. Since pure gold is inherently soft, the addition of these alloys makes the final material much harder and more resilient to daily wear. This allows for the creation of intricate jewelry designs that would be impossible with 24K gold alone.
The two most common alloying metals used to create white gold are nickel and palladium, each offering distinct properties. Nickel-based white gold is known for its hardness and strength, making it a less expensive option for durable items like rings and pins. However, nickel can cause an allergic skin reaction in a small percentage of the population, which has led some countries to restrict its use in jewelry.
Palladium-based white gold is the more premium formulation, substituting the nickel with palladium, a rare metal in the platinum group. This results in a softer white tone and a hypoallergenic material, making it a better choice for those with skin sensitivities. Palladium alloys are generally more expensive due to the metal’s rarity and can sometimes include small amounts of silver or copper to fine-tune the final properties.
Regardless of the alloy used, the combination of yellow gold with these white metals typically results in a finished product that is not a bright, pure white, but rather a dull, slightly grayish, or pale yellow tone. This off-white color is the natural appearance of the alloy before the final finishing step is applied. The specific combination of non-gold metals determines the exact base color and the durability of the piece.
The Rhodium Plating Finish
To achieve the bright, lustrous, icy-white appearance, nearly all white gold jewelry undergoes a process called rhodium plating. Rhodium is a highly reflective, silvery-white metal that belongs to the platinum family. It is applied to the surface of the white gold alloy through an electroplating bath.
This thin, hard layer of rhodium acts as a mirror-like finish, covering the underlying grayish or yellowish tint of the gold alloy. The electroplating process bonds the rhodium atoms to the surface, creating a protective barrier that is also scratch-resistant. Rhodium is also hypoallergenic, providing an extra layer of protection for individuals sensitive to the nickel alloy underneath.
The rhodium plating is not permanent; it is a surface coating that will gradually wear away over time, particularly on high-friction areas like the underside of a ring shank. When the rhodium wears thin, the natural, warmer color of the white gold alloy begins to show through, often appearing as a slight yellowing. To maintain the bright white color, white gold jewelry typically requires re-plating every 12 to 18 months, depending on how frequently the piece is worn.