Aluminum and copper do not rust, but they do corrode. Brass doesn’t rust but exposure to air causing it to develop a blue/green patina. Bronze doesn’t rust. Gold, platinum, and silver contain no iron and consequently do not rust naturally. They’re also resistant to corrosion. Stainless steel is an alloy, so it must contain at least 11% chromium oxide to protect it from rusting. Other additives can protect it from corrosion.
These metals can be used as rust and corrosion proof jewelry and can easily be made into a waterproof necklace. Not only can metals be used to form chains or links that form jewelry, leather, plastic, or string can be used to hold glass, wood, natural gems, or plastic beads. All these constructions can form waterproof jewelry. While they will all get wet, none of them will be destroyed or harmed by being immersed in fresh, salt water, or chlorine treated water.