A method of producing a security device comprises ink jet printing a liquid crystal material onto a first region 1 of a substrate and ink jet printing the same liquid crystal material onto a second region 2 of the substrate; the volume of the liquid crystal material printed per unit area of the substrate in the first region 1 is different to the volume of the liquid crystal material printed per unit area in the second region 2 of the substrate such that the wavelength of the peak reflectance of the liquid crystal material is different in the first and second regions. Each region displays a different colour when viewed. The liquid crystal material is preferably cholesteric and the regions preferably appear different when viewed from different angles. A security device and authentication method of security device including first and second regions as detailed above is also disclosed.