Most body piercing jewelry consists of rings, hoops, studs, or barbell-shaped ornaments. The size and shape of jewelry is determined by the body site pierced and personal preferences. Jewelry is not always interchangeable between piercing sites. In particular, jewelry designed for ear piercing may not be suitable for another part of the body because of the length of the post or the pressure exerted by the clasp. Most body piercing jewelry is made of metal, usually stainless steel, gold, niobium, titanium, or alloys. Surgical stainless steel rarely causes allergic skin reactions; however, not all stainless steel products are nickel-free.15 Gold often is combined with nickel or other metals to make alloys that have improved hardness and durability. Nickel in gold-filled or gold-plated jewelry is associated with a high prevalence of reactivity in persons who are nickel sensitive. Consumers must pay careful attention to the stud or clasp on earrings; jewelry with a high karat rating commonly is paired with less expensive gold-plated studs or earring backs. Niobium and titanium are lightweight elemental metals that rarely produce an allergic response. Other features to consider in body piercing jewelry include ease of removal (in case of trauma or radiographs), surface smoothness, and its capacity to withstand autoclaving and cleaning
