When buying a titanium ring, there are a few issues you should consider. There are both positive and negative aspects to titanium jewelry. In general, most people consider purchasing titanium wedding bands, though you can apply this information to any titanium ring.
Titanium is a very lightweight metal, and will feel lighter on the finger than a gold or platinum ring. It is also considerably less expensive than gold or platinum, though the price difference may or may not be remarkable because working with titanium takes considerably more time than working with gold or platinum. Titanium can also be colored, if you want a black or blue titanium ring for example.
The first thing to remember is to size your titanium ring very carefully, because the ring is made of a solid piece of metal, not soldered together at two points like most metal rings. This means that the ring cannot be re-sized if you've ordered the wrong size. It can be made slightly larger by removing some of the metal on the interior of the ring, but the rings cannot be made smaller. Titanium rings can be cut off in an emergency, however.
Titanium rings are great for those with metal allergies, because titanium is hypoallergenic. In addition to jewelry, it is used for surgical implants. Titanium is a very strong metal, but it will show scratches and wear. However, any scratches can easily be polished out by a professional jeweler, and titanium will not need to be re-coated with rhodium plating the way white gold does. The rhodium coating gives white gold its silver appearance, but titanium is naturally a dark silver, similar in appearance to stainless steel.
Titanium rings can be customized, such as with gold inlays or with small diamonds or other jewels set into the bands. This needs to be done at the time of manufacture. Titanium cannot be made into a prong setting, so it is not traditionally made into engagement rings. One option to save money is to have the groom's ring made out of titanium, and the bride's engagement ring and wedding band made out of white gold or platinum. The rings will appear similar, but the groom's wedding band will be less expensive and stronger.