When titanium’s natural clear oxide film is increased through anodic oxidation, color is created by the phenomenon of light interference – the rainbow principle. We observe the phenomenon of interference color almost every day, but usually do not realize what’s at hand behind the rainbow display of color produced when light waves interfere with each other.  One of the best examples of interference color can be seen when light reflects from the film produced by oil floating on water. Another example can be observed in the film of a soap bubble, which reflects a spectrum of beautiful colors when illuminated by natural or artificial light sources.  As light rays travel through the film, they are partially reflected, refracted and absorbed.  The reflected rays differ in phase, creating interference that we see as colors. There are no coatings or dyes involved. As the film thickness increases, the color changes – from bronze, to green, to red-violet, through the full range of spectral colors.  Its inherent beauty is unsurpassed across a palette of colors that range from subdued to vibrant.