18ct Yellow Gold and Bio-plast Nose Stud. For use in the Nose Piercing. This nose stud is 0.8mm gauge and comes with a straight and a curved bio-plast stem and is supplied with a push fit 18ct Yellow gold plain ball. (Bio-plast is a flexible plastic specially developed for use inside the body. It is used to make comfortable attractive body jewellery which minimises irritation.) For help with sizing please read our Sizing Guide. High quality 18ct Gold Nose Stud.