Zirconline® is colored jewelry, they are not "colored" in the classic sense, it is 316L Steel that is covered with a thin plasma film (PVD coating). The thin film is very strong and does not fade. The technology has been used since the late 80's and is used, among other things, for orthopedic implants to provide an extra durable surface.
Looks just like Gold, and is incredibly popular in our webshop.