Titanium

The hardest and highest grade of metal with virtually no presence of nickel (less than .05%). The strength of the metal makes it practically impervious to scratches and imperfections. Titanium is also the most expensive metal used for body jewellery, but is certainly worth the price for someone who is hyper-sensitive to nickel-containing metals and can’t wear anything else.

Titanium jewellery is also lightweight (around 60% the weight of stainless steel given the same volume), it is highly corrosion resistant and less likely to react with body fluids, is not magnetic, it can be anodized to create a layer of coloured oxide on the surface. Common colours are yellow, blue, purple, green, and rainbow. Titanium can be sterilized in an autoclave.

The pure qualities of titanium have long been used for both piercings and surgical implants, and very few long-term allergies and other complications have been reported, though as with any material they could arise after prolonged contact with the human body.