In the decorative field, besides the optical characteristics needed for achieving desired colours, the material should have suitable properties able to assure the daily use of the component without significant degradation. Oxides are well known materials with a high wear and corrosion resistance which make them a preferential choice of coatings for environmental protection. However, the intrinsic colours possible to be achieved in a single oxide system are very limited. For example in W-O system, besides the different tonalities of grey, only the dark blue can be obtained for slightly substochiometric WO3 compound. The pallet of colours exhibited by WO3 coatings is due to interferometric effects. Recently, it was shown that playing with the gradient of the chemical composition of W-O layers it was possible to tune the global colour of the coatings, which made this system an attractive candidate for decorative applications.