Sterling silver and brass keycaps can be cleaned and shined using a jewelry polishing cloth. Always store each Keycap separately when not in use. Valued as a precious metal, sterling silver may oxidize when exposed to salty air, humidity, perspiration, cosmetics, chlorine, sulfur, bleach and or other strong chemicals to name a few. To preserve its appearance and longevity. Gently rubbing silver with a silver polishing cloth will remove oxidation and restore shine. If necessary, you may apply a small amount of silver cleaner to a soft silver polishing cloth, gently rub the silver with the cloth several times, wipe using warm water with a clean soft cloth, blot dry and shine your silver with a clean silver polishing cloth.