a metal, gray in color, that is used for watch cases and bracelets. Much stronger and lighter than stainless steel and hypoallergenic. It is 30% stronger and 50% lighter than steel. It is very resistant to saltwater corrosion, making it useful for divers’ watches. Although it can be scratched easily, some manufacturers use a coating to resist scratching. Grade 2 is unalloyed pure titanium, and Grade 5 is made of an alloy. Both are commonly used in watchmaking.