White gold is a popular jewelry metal, valued for its bright, silvery-white appearance and durability. It is not pure gold but an alloy, a mixture of gold with various other metals. The specific composition of this alloy determines its physical characteristics, including whether it interacts with a magnetic field.
White Gold: Composition and Alloys
White gold is created by blending pure yellow gold with white metals to lighten its color and increase its strength. Purity is measured in karats; 18-karat white gold contains 75% pure gold, and 14-karat contains 58.3% gold. The remaining percentage consists of alloying elements that provide the white hue and necessary hardness.
The most common white metals used are nickel, palladium, silver, and copper. Nickel alloys are strong and hard, though their use is sometimes restricted due to allergic reactions. Palladium-based alloys are generally softer and more pliable, often preferred for setting gemstones.
How Magnetism Works in Metals
Materials are categorized by how they respond to an external magnetic field. Ferromagnetic materials, which include iron, nickel, and cobalt, are strongly attracted to magnets and can retain their magnetism. This attraction is due to the spontaneous alignment of electron spins within organized regions called domains.
Paramagnetic materials, such as platinum and palladium, are only weakly attracted to a magnetic field, and this attraction disappears once the external field is removed. In contrast, diamagnetic materials, including pure gold, silver, and copper, are actually repelled by a magnetic field. This repulsion is extremely weak and not noticeable in everyday testing.
The Magnetic Status of Pure White Gold
Standard white gold jewelry is generally not ferromagnetic and will not stick to a household magnet. While pure gold is diamagnetic, the alloying process introduces other elements, notably nickel, which is a strongly magnetic metal. However, the nickel atoms are dispersed within the much larger volume of non-magnetic gold and other metals. This dispersal prevents the formation of the organized magnetic domains necessary for bulk ferromagnetism to occur.
Even in nickel-containing white gold, the magnetic influence is usually negligible. This is especially true in higher purities like 18-karat, where the percentage of non-gold metal is lower.
Why White Gold Might React to a Magnet
If white gold jewelry shows a reaction to a magnet, the attraction is often caused by components other than the gold alloy. The most frequent reason is the presence of clasps or findings made from steel. These attachment mechanisms, such as lobster clasps, are often crafted from base metals to ensure strength and durability, and steel is highly ferromagnetic.
Another possibility is a lower-quality alloy containing a disproportionately high amount of nickel or other ferromagnetic impurities. A significant concentration of nickel, sometimes used in cheaper alloys, can create a slight magnetic response. However, this faint magnetic pull is far less powerful than a magnet sticking to a piece of iron.