Titanium rings can develop a black color or tarnish over time due to exposure to oxygen, moisture, or other environmental factors. This is a natural process known as oxidation and can occur with any metal, including titanium.

However, unlike other metals that may rust or corrode when exposed to these elements, titanium forms a protective layer of oxide on its surface that helps to prevent further corrosion and damage to the metal. This layer of oxide is what gives titanium its characteristic grayish-blue color.

In some cases, titanium rings can develop a darker black color if they are exposed to high levels of heat or chemicals. This can cause the oxide layer to thicken and darken, resulting in a black or dark gray color on the surface of the ring.

To maintain the appearance of a titanium ring and prevent discoloration or damage, it is recommended to clean the ring regularly with mild soap and water and to avoid exposing it to extreme heat or chemicals. If you notice significant discoloration or damage to your titanium ring, it is best to take it to a professional jeweler for repair or maintenance.