Gold, cherished for its enduring luster, often raises a common question: does it tarnish? While pure gold maintains its brilliance, most gold jewelry is more nuanced. Other metals mixed with gold significantly influence whether it loses its shine.
The Unreactive Nature of Pure Gold
Pure gold, 24-karat gold, is a noble metal due to its chemical inertness. Its stable electron configuration makes electrons less prone to bonding. This stability means pure gold does not react with oxygen, sulfur, or moisture in the air.
This resistance prevents pure gold from oxidizing or corroding, processes that lead to tarnishing in many other metals. A 24-karat gold piece will not rust or tarnish, retaining its original sheen after prolonged environmental exposure. Its atomic structure preserves its bright appearance.
The Role of Alloys in Gold Tarnishing
Most gold jewelry is an alloy, a mixture of gold with other metals. Pure gold is soft and malleable, impractical for everyday wear. Alloying gold with metals like copper, silver, nickel, palladium, or zinc increases hardness, durability, and can alter its color.
Gold purity is measured in karats; 24 karats represent pure gold. For example, 18-karat gold contains 75% pure gold, while 14-karat gold has 58.3% pure gold, with the remainder being other metals. These non-gold metals react with environmental elements, leading to tarnishing.
Exposure to sulfur compounds in air pollution, foods, and cosmetics can form a dark surface layer, such as silver sulfide or oxidized copper. Chlorine in swimming pools and cleaning products, along with sweat, lotions, and perfumes, accelerate this reaction, causing dullness or discoloration. Lower karat gold, with more reactive metals, is more susceptible to tarnishing than higher karat gold.
Protecting Your Gold from Tarnishing
To maintain the luster of gold jewelry, especially alloyed pieces, take preventative measures. Remove jewelry before activities involving chemicals or moisture. This includes swimming in chlorinated water or saltwater, showering, cleaning with household products, and exercising, as sweat contributes to tarnishing. Apply cosmetics, perfumes, or lotions after putting on jewelry to minimize contact.
Proper storage prevents tarnish. Store gold jewelry in a cool, dry, dark place, ideally in individual soft pouches of velvet or microfiber, or a fabric-lined jewelry box. This prevents scratching and limits exposure to air and humidity. Anti-tarnish strips or silica gel packets absorb moisture and harmful compounds.
Regular, gentle cleaning with warm water and mild dish soap, followed by drying with a soft, lint-free cloth, removes dirt and oils. For persistent tarnish, professional cleaning restores brilliance.