Homogeneous and transparent protective coatings for precious metals and copper alloys and techniques for forming the coatings on precious metals and copper alloys are provided. In an embodiment, ionic oxide film is deposited onto a surface of a substrate including a metal, such as a precious metal and/or a copper alloy, using pulsed chemical vapor deposition (PCVD). A homogenous and transparent solid film based on ionic oxide is formed on the surface of the substrate in response to the depositing.