Gold, designated Au on the periodic table, has been prized for millennia for its remarkable resistance to decay. It is classified as a noble metal, meaning it is nearly unwilling to react with other substances, which is why it retains its luster over vast periods. Many people wonder if exposure to a common element like water can damage their treasured gold possessions. The answer depends entirely on the gold’s purity and the specific type of water involved. Understanding the underlying chemistry provides the practical knowledge needed to protect gold items from discoloration and corrosion.
The Chemistry Behind Gold’s Inertness
Pure gold, specifically 24-karat gold, remains unaffected by exposure to plain water, oxygen, or general atmospheric moisture. This exceptional stability is a direct result of its atomic structure, making it one of the least reactive metals known. The atoms of gold hold their outer electrons with great tenacity. Oxidation, the process that causes metals like iron to rust or silver to tarnish, requires a metal to readily lose electrons to another element, such as oxygen. Because gold’s electrons are so tightly bound, it does not easily surrender them to form chemical bonds with water or atmospheric oxygen. This stability ensures pure gold never tarnishes or rusts, allowing ancient gold artifacts to look nearly as brilliant today as they did when they were first created.
Why Gold Jewelry Still Tarnishes and Corrodes
Gold jewelry dulling or tarnishing is a consequence of manufacturing, not a contradiction of gold’s noble properties. Pure 24-karat gold is inherently soft and malleable, making it impractical for everyday wear. Therefore, it is combined with other metals—such as copper, silver, nickel, and zinc—to create a more durable and harder material known as an alloy. The karat system indicates the proportion of pure gold in the alloy, where 24 parts represent 100% purity. For example, 18-karat gold is 75% pure gold, while the more common 14-karat gold is only 58.3% gold. These non-gold metals, especially copper and silver, are chemically reactive and are the true source of tarnish and corrosion when exposed to moisture and air. The base metals oxidize, creating a dull film on the surface that diminishes the gold’s shine.
Specific Risks Posed by Chlorinated and Salt Water
While a quick rinse in plain water will not harm gold jewelry, specific types of water contain agents that attack the base metals in gold alloys. Chlorinated water, commonly found in swimming pools and hot tubs, presents a significant risk because chlorine is a powerful oxidizing agent. It rapidly reacts with the silver and copper in the alloy, accelerating the corrosion process far beyond what simple air exposure would cause.
Prolonged exposure to chlorine can lead to chemical degradation and discoloration, often causing the jewelry to appear dull or even develop a white, chalky appearance. The corrosive action can also weaken the structural integrity of the metal, making prongs that hold gemstones brittle and susceptible to breaking. Salt water, such as that found in the ocean, poses a different threat, causing a slower but persistent form of degradation. The salt and mineral content can wear away at solder joints and leave behind persistent deposits that dull the finish, requiring professional cleaning to restore the item’s original luster.
Essential Care and Cleaning for Gold Items
Protecting gold jewelry from water damage primarily involves preventing contact with the corrosive agents found in water and household products. Remove all gold items, especially lower-karat pieces, before entering swimming pools, hot tubs, or the ocean. They should also be removed before showering, as soaps and shampoos can leave a dulling film or contain ingredients that accelerate tarnishing.
When cleaning your gold items, simple is always best to avoid damaging the alloyed metals. Clean your jewelry using a solution of warm water and a few drops of mild dish soap, gently rubbing the surface with a soft cloth or a soft-bristled brush. After cleaning, rinsing the piece thoroughly under clean water is necessary to remove all soap residue. Completely dry the jewelry with a soft cloth before storing it in a dry environment to prevent moisture from initiating the tarnishing process on the susceptible base metals.