Be careful with the products you buy for your baby!!! Nickel is a hard, shiny, white metal that imitates silver. Nickel is easy to process and, because of its low cost, it is used frequently. For this reason, it is used in metal jewelry and, unfortunately, in the manufacture of snap fasteners and zippers in baby products. Nickel is the most common cause of the allergic skin rash called allergic contact dermatitis (allergic contact eczema) and poses a significant problem for your baby.