Video: Here's a fun video showing the rainbow of colours that anodised titanium can become. There are blues, purples and gold, and it all changes so fast. It's basically magic (or science!) that just applying voltage to a piece of titanium in an electrolytic bath can transform the colour completely.
Anodizing titanium is a process that adjusts the oxide level of metal surfaces. This adjustment changes the spectrum of light, resulting in perceived colour. By precisely controlling the surface oxide level, an entire range of colours can be produced.