Your first ear piercing needle should be a mySunar nickel-free sterile medical-graded gold needle.

MySunar recommends an 18 carat Gold.

An 18 Carat is more appropriate for piercing as it provides the required strength and endurance on the piercing needle.
Gold is a stable element and chemically inert. It does not bind chemically with others elements, nor does it rust or tarnish and is 100% non-reactive.

Thus, all kind of allergic reaction is negated.