Titanium is divided in different grades depending on which metals it is alloyed with. The only suitable for implants and piercings in the human body is grade 23 (TI6AL4VELI). This is a grade recognised by standard societies world wide for medical devices. Heart valves, pacemakers and replacement human body parts are being made of Grade 23 Titanium. Titanium is suitable for sensitive and very allergic people. It is very light in weight and can be coloured. It is known as one of five substance that is accepted best by the human body.