It is a common misconception that gold will never change color, but this is only true for the purest form of the element. While 24-karat gold remains chemically stable and does not tarnish, jewelry made from 14-karat gold often shows signs of discoloration over time. This change is not a flaw in the gold itself, but a normal reaction involving the non-gold metals mixed into the alloy. The presence of these other metals makes 14K gold susceptible to environmental reactions that lead to a noticeable change in appearance.
What Makes Up 14K Gold
The “K” in 14K gold refers to karat, a measure of the proportion of pure gold within the metal alloy. By definition, 14K gold is composed of 14 parts pure gold and 10 parts of other metals, based on a total of 24 parts. This ratio means that 14K gold has a purity of approximately 58.3% gold, with the remaining 41.7% consisting of various alloying agents.
These additional metals are incorporated to enhance the gold’s durability and alter its color, since pure gold is too soft for everyday wear. The non-gold components typically include copper, silver, zinc, and sometimes nickel or palladium. For example, rose gold alloys use a higher proportion of copper, while white gold incorporates metals like silver or palladium to achieve a whiter tone. These chemically reactive elements are the reason 14K gold jewelry can discolor, as they are not as stable as the gold component.
The Chemistry Behind Discoloration
The discoloration observed on 14K gold is a surface phenomenon, where the alloying metals react with compounds in the environment to form a thin film. This process is not the gold changing color, but rather the creation of corrosion products on the surface of the copper and silver components. The pure gold portion remains largely unaffected due to its status as a noble metal, which means it resists chemical attack and oxidation.
Two primary reactions are responsible for the change in color: oxidation and sulfidation. Oxidation involves the copper in the alloy reacting with oxygen and moisture in the air. This reaction forms copper oxide, which often manifests as darkening or a slight green tint on the jewelry’s surface. Sulfidation occurs when the silver component reacts with sulfur compounds present in the atmosphere and various chemicals. This interaction creates silver sulfide, a dark compound recognized as black or dark gray tarnish.
Everyday Triggers That Cause Tarnish
The reactions that cause 14K gold to tarnish are accelerated by exposure to several substances. Chlorine is one of the most aggressive triggers, found in swimming pools, hot tubs, and many household cleaning products. Exposure to chlorine can cause rapid discoloration and may even weaken the metal structure over time.
The natural oils and salts present in human sweat react with the copper and silver alloys. Sweat is slightly acidic and contains chemicals like ammonia and urea. Common cosmetics and personal care products, such as perfumes, hairsprays, and lotions, can leave a chemical residue on the jewelry. This film traps moisture and accelerates the reaction between the alloy metals and environmental compounds.
Cleaning and Maintaining 14K Jewelry
Restoring the luster to 14K gold jewelry typically involves removing the surface layer of tarnish and residue through gentle cleaning. A simple, effective method utilizes warm water mixed with a few drops of mild dish soap. The jewelry should be soaked in this solution for about 10 to 20 minutes to loosen any grime and then gently scrubbed with a soft-bristled brush. After cleaning, it is essential to rinse the piece thoroughly under clean water and dry it completely with a soft, lint-free cloth to prevent water spots.
To prevent future discoloration, jewelry should be removed before swimming, exercising, or engaging in household chores that involve chemical cleaners. When not being worn, 14K gold pieces should be stored separately in a cool, dry place, ideally in a lined jewelry box or anti-tarnish pouch. Regular wiping with a soft jewelry cloth after each wear helps remove body oils and dust before they can initiate a chemical reaction.