Anodizing is a process that adds color to an object made in titanium. It is a different process than what is used in aluminum anodizing, where dyes are added to an oxide layer. In titanium anodizing, an electrical current is applied to a conductive bath, and the object, such as a ring is suspended on a hook. As DC voltage is applied, a clear oxide layer forms on the titanium. As the voltage increases, the thickness of the layer also increases, and a color due to interference of lightwaves is produced. The oxide is such a thickness as to constructively interfere a specific color, and destructively interfere all others. In this way, a very pure blue, purple, and other colors are produced in a similar manner to a soap bubble or oil spilled on a wet parking lot. Since the oxide layer is also an electrical insulator, once a specific voltage is reached, colors of lower voltages will no longer be formed, even as the voltage is lowered. Not all colors are possible. Pure reds, greens, or blacks are not possible by anodizing. The anodized spectrum includes a bronze, blue purple, blue, light blue, yellow, magenta, and teal. Voltages range from around 10 volts to around 120 volts to get those colors. The oxide layer is extremely hard, although it is also extremely thin. Because it’s so thin, the coating nets out being about as hard as glass, so it is not recommended to be used on an outer surface of an item to see wear like a ring. In the case of a ring, anodizing is normally done down in grooves, or on the inner diameter of a ring, where it won’t see wear. The anodizing is an extremely inert surface, so is hypoallergenic and is safe for people with allergies to nickel or other triggers. Here is a link to some anodized titanium rings: http://www.boonerings.com/carved.htm Titanium is one of only a few metals that can be anodized in this way. Others include zirconium and niobium, and are called the reactive metals for this attribute.