For sensitive skin
All jewellery in this category are hypoallaergenic.
Very rarely people are allergic to titanium and even in those cases it's mostly not the nickel in that metal that presents the problem.
People are never allergic to glass(be it Soda-Lime glass or Pyrex glass).
Silicone is also a hypoallergenic material. Although this material is not to be used for stretching. Silicone O-rings are entirely harmless to be worn on jewellery that was used for stretching or other.
Bioplast is one of the few plastics that are hypoallergenic.
Organics are materials of natural origin, such as:
Read more about organics on the Soesha website
PTFE is another hypoallergenic material that is entirely inert and bio-compatible. PTFE is aslo used in the manufacturing of medical implants.