According to Gillett's Jewellers, while titanium is much stronger than platinum, silver and gold, it is not completely scratch resistant. Titanium has a rating of six on the Mohs Hardness Scale, while gold is a mere three and platinum 4.5.
According to TungstenWorld.com, tungsten is the hardest metal available for rings, and the metal has a Mohs rating between eight and nine, which makes it the most scratch-resistant product. Like gold rings, titanium rings can be polished by jewelers so that the finish looks new again. Titanium rings are available in a satin finish, which does not prevent scratching, but helps to protect the color finish.