Tips to Protect Your Gold Jewelry

What Causes Stress Corrosion?

Frequently our customers ask questions regarding the loss of stones due to prong failure, the effects of chlorine, and other chemicals on jewelry.

It’s summertime. Hot, lazy days hanging out by the pool or spa with something cool to drink. And of course, making a fashion statement with as much jewelry as possible shown off against a beautiful tan.

Chlorine is extremely detrimental to karat metals and should be avoided. Special care should be taken with detergents, cleaners, and other industrial or household formulas. Consider that levels of chlorine and other chemicals can be increased by evaporation of fluids, leaving concentrated deposits. In particular, this makes spas and swimming pools undesireable for gold jewelry.

Alloy Factors

Stress corrosion is very common in low karat alloys, characterized as 10K or less. In alloys with gold atomic content of 40 percent or greater it is almost non-existent. Alloy systems have a significant impact as well. For example, it is more common in white gold, which is affected by the nickel content. Nickel contents below 7 percent and above 10 percent are very susceptible. As a rule, 8 to 10 percent are standard nickel levels in a 14K white system.

Another factor is whether the metallic system is homogeneous. Cast structures are not usually considered homogeneous due to micro and macro segregation. Cold work followed by proper annealing can help reduce this; the more times repeated, the more homogeneous the system becomes.

Stress Factors

Technically, stress can be defined as fluctuating strains in a metallic system, which work against each other to create a nucleation for possible failure.

Mechanical deformation is a primary source of stress: bending, stamping, drawing, rolling, and hammering. The quantity of deformation has an impact, as does the dispersion of isolation of the stress to one area. It seems that isolated stress increases the potential for failure under the proper conditions.

Heating is often overlooked as a source of stress, not to mention the segregation of the metallic system. Overheating, length of heating, and repeated heating encourages grain growth and segregation within the crystalline structure. Isolated heating of strained metal could also be cause of varying stress levels. Careful consideration should be given to cooling rates of heated areas. The source of heat can vary from bench torch soldering to gringing.

Notching has been studied at length in application to structural assemblies, and should be applied to jewelry fabrication. Notches and cuts, which come to a sharp angle, are undesirable due to the concentration of stress at the points of intersection. A small radius helps to distribute the stress over a wider area.

Compression is a factor rarely considered. Stretching and compression combined, along with quantity of compression, can cause failure.

Corrosion is the reduction of metals to a metallic salt. In gold jewelry, aqueous or gaseous environments can cause it. Stressed areas are possible sites of fracture, acting as entry routes for corrosives.

Mercury is a great example of wet metal corrosion, as is the exposure of copper-based alloys to liquid bismuth. The liquid metal migrates through the metallic structure, propagating a fast fracture.

Chlorine is extremely detrimental to karat metals and should be avoided. Special care should be taken with detergents, cleaners, and other industrial or household formulas. Consider that levels of chlorine and other chemicals can be increased by evaporation of fluids, leaving concentrated deposits. In particular, this makes spas and swimming pools undesireable for gold jewelry.