Titanium is an element (symbol Ti) like gold, silver and platinum. It is a silvery white non ferrous metal with the highest strength to weight ratio of any known element. Titanium is inert and therefore completely corrosion resistant. It does not react to salt water, sunlight, or any body or common chemistry.
Titanium is incredibly strong, far stronger than other conventional materials. Titanium is also harder than most other conventional metals. It does scratch, but not as easily as silver, gold or platinum. Also, titanium is lighter and therefore more comfortable to wear than other materials.
Titanium is the most biocompatible (hypoallergenic) element available for jewelry and will not irritate even the most sensitive skin. Unlike other jewelry materials, titanium does not need to be combined with other alloys to harden it. These alloys can create negative reactions with our body chemistry. Titanium is inert and non reactive to almost all chemicals.
Titanium is a light-weight and strong metal and ranges from gray to silver in color. Polished titanium is very close to Platinum, just a few shades darker. Brushed finish makes titanium look a bit darker, so is sandblast finish, almost gun-metal color.
Titanium is naturally platinum gray. By applying heat or electricity one may unleash its refractive properties by inducing various oxide thicknesses on the material surface. The resulting titanium oxide causes an optical interference with a purity and vivacity much the same as witnessed in the luminescent colors of oil on water, a peacock's feather, or a rainbow. The colors are directly related to time and voltage. This process is called anodization.
Titanium is a reactive metal that can be anodized in different colors by electrolysis or thermal treatment. Unfortunately this type of surface treatment is not permanent. An anodized titanium ring would look good initially, but can appear scratched and discolored with wear. Anodization is just an oxidation layer on the metal, so the color is more an optical illusion. It can just be the friction it encounters, or your body's natural acidity that wears the oxidized layer away. It will not hurt you, it is not dangerous. It's just the nature of anodization.
How quickly the anodization wears off depends on exposure. Anodized titanium can react to chemicals, such as lotion, acid, perfume, etc. One trick is to paint the surface area that touches the skin or more exposed to environment with clear nail polish.
Titanium itself will not change color or tarnish. However, any colored (anodized) area is not scratch resistant. Black titanium is not anodized. It is a permanent, scratch resistant solution.
Titanium jewelry can be cleaned with any non abrasive soap or cleaner. Anodized titanium rings are best cleaned with warm soapy water the dried with a soft tissue. It is also safe to clean titanium in an ultrasonic or steam cleaner. Titanium is inert and will not react or change color while swimming in a pool.