When gold jewelry develops a noticeable pink or reddish discoloration, it is a common yet concerning event. This change is often mistaken for the gold itself tarnishing, but pure gold is a noble metal, meaning it is highly resistant to chemical reactions like oxidation and corrosion. The phenomenon is entirely related to the metals mixed with the pure gold to create a functional alloy, resulting in a surface-level chemical reaction happening within the non-gold components.
The Role of Gold Alloys and Karats
Gold in its purest form, 24-karat (24K), is too soft for everyday wear, making it susceptible to scratching and deformation. To add strength and durability, it is alloyed with other metals such as silver, nickel, zinc, and copper. The karat system indicates the proportion of pure gold in the alloy, with 18K gold containing 75% pure gold, and 14K containing 58.3% pure gold.
The choice of alloy metals dictates both the final color and the susceptibility to discoloration. Copper is often used in yellow gold alloys to increase strength. However, copper is the metal most responsible for the unwanted pink or red surface change because it is highly reactive compared to gold.
The Chemistry Behind the Pink Color
The appearance of a pink or reddish layer on gold jewelry is a clear sign of copper oxidation, a process sometimes referred to as “red rot.” This discoloration occurs when the copper atoms in the alloy react with oxygen, moisture, or sulfur compounds in the environment. The resulting compound is a form of copper oxide, which settles as a reddish film on the surface of the jewelry.
The actual gold atoms, which are highly stable, remain chemically unaffected and do not degrade. The copper is selectively corroded, meaning the corrosive elements are reacting only with the copper component of the alloy. This process is more prevalent in lower-karat gold, like 10K or 14K, because they contain a higher concentration of copper.
Common Triggers for Accelerated Corrosion
A variety of environmental and personal factors can significantly speed up the copper corrosion process. Exposure to chlorine is a major catalyst, as the chemical readily reacts with copper, making swimming pools and strong household cleaning products particularly damaging to gold alloys. Even low concentrations of chlorine can initiate the reaction over time.
The body’s own chemistry also plays a role, especially sweat and skin oils, which contain salts and acids that accelerate the breakdown of copper. Products applied directly to the skin, including perfumes, lotions, and hairsprays, contain chemical compounds that can interact with the copper alloy. Furthermore, exposure to high humidity or air pollution that contains sulfur compounds can also promote the formation of copper oxides and sulfides.
Reversing and Preventing the Color Change
For light, superficial pink discoloration, a simple at-home cleaning can often resolve the issue. Soaking the jewelry in warm water mixed with a few drops of mild dish soap can loosen the surface tarnish. Following the soak, a gentle scrub with a soft-bristled brush can safely lift the residue.
When the corrosion, or “red rot,” is deep or has penetrated below the surface, professional intervention is necessary. Jewelers can use specialized polishing compounds to remove the oxidized layer. In severe cases, a process called electrostripping may be required to chemically remove the degraded metal. If the piece is heavily worn or has a low gold content, the best long-term solution may be to have the jewelry professionally replated with a fresh layer of gold.
To prevent future discoloration, the most effective strategy is to minimize contact with corrosive agents. It is advisable to remove all gold jewelry before swimming in chlorinated water, using household chemicals, or applying cosmetics and lotions. Storing jewelry in a cool, dry place will also slow down the natural oxidation process. Regular, gentle cleaning to remove corrosive residues like sweat and body oils helps maintain the alloy’s original intended color.