Pure gold, or elemental gold (Au), is chemically inert, meaning it resists reacting with oxygen, water, or compounds found on the skin. This stability makes gold odorless and non-tarnishing. The metallic scent perceived actually comes from a volatile byproduct of a chemical reaction between the jewelry’s non-gold components and the wearer’s skin.
The Science of the Metallic Scent
The metallic odor is generated by a complex interaction with the skin’s surface, not by the metal vaporizing. When a reactive metal touches the skin, it causes the oxidation of skin lipids (natural oils and fats in sweat). This process breaks down the lipids into highly odorous, volatile organic molecules.
The primary compound responsible for the metallic smell is 1-octen-3-one, a molecule detectable even in small concentrations. This ketone is the reduction product of skin lipid peroxides and reactive metal ions, creating the distinct scent associated with handling metal.
The Common Alloy Culprits
Pure 24-karat gold is too soft for durable jewelry, so it is combined with other metals to create an alloy for strength and wear resistance. These non-gold metals are the source of the metallic reaction and subsequent smell.
Copper is a common alloy, especially in rose gold and lower-carat yellow gold, and reacts highly with sweat. Nickel is another frequent component, used to create white gold and add strength. Zinc is also occasionally included in gold alloys and contributes to the metallic odor. The presence of these reactive metals enables the skin lipid oxidation process, creating the volatile 1-octen-3-one compound.
How Purity Affects the Odor Intensity
The intensity of the metallic scent relates directly to the gold’s purity level, measured using the karat system. This system indicates the proportion of pure gold out of 24 total parts. For example, 24-karat gold is nearly 100% pure and is odorless because it lacks reactive alloys.
Lower karat numbers contain a higher percentage of reactive non-gold metals, increasing the potential for the odor-causing chemical reaction. Ten-karat (10K) gold, a common jewelry grade, is only 41.7% pure gold; the remaining 58.3% consists of reactive alloys like copper and nickel. Jewelry made from this lower-purity gold will produce a much stronger metallic smell than pieces made from 18-karat (75% pure gold) or 14-karat (58.3% pure gold) gold.
Practical Ways to Minimize the Smell
Cleaning and Drying
Regular cleaning of gold jewelry significantly reduces the metallic scent by removing accumulated oxidized compounds and skin oils. Using mild soap and warm water washes away the chemical residues that feed the odor-producing reaction. Ensuring the jewelry is thoroughly dried after cleaning and whenever it gets wet also limits the oxidation of reactive metals.
Barrier Methods
Minimizing direct skin contact is another solution. A thin, clear barrier coating can be applied to the metal surface that touches the skin. Products like specialized jewelry sealants or clear nail polish prevent the alloys from reacting with sweat. Storing gold items in a dry environment helps prevent oxidation when the piece is not being worn.