Anodizing titanium is a process that adjusts the oxide level of metal surfaces. This adjustment changes the spectrum of light, resulting in perceived color. By precisely controlling the surface oxide level, an entire range of colors can be produced. Anodizing titanium is not a coating, nor does it use dyes.
More simply put, it’s changing the viewed color of titanium by letting the item go swimming in a pool of water with electricity flowing through it. Different voltages give you different colors.
Materials that can be anodized are: Titanium, Zirconium, Niobium, and Hafnium.