Tungsten Carbide has a metallic, silvery tone. Tungsten is a very hard and it's 4x harder than titanium and 2x harder than steel. Despite its hardness, tungsten can shatter with pressure or upon impact in some situations. This is because of how it is produced. Tungsten and carbide are ground to a powder, bound together using nickel, and compressed into a solid state, making it porous, brittle, and susceptible to shattering.
Titanium has superior structural integrity and is 3x stronger than steel. Titanium is very light weight (1/3 as much as gold). Although a very hard and durable metal, titanium can still be scratched by abrasive materials like rocks or hardened steel tools.
Titanium also plays a role in gems. Traces of titanium dioxide impurities cause the asterism phenomenon in Star Sapphires and Rubies. Blue sapphires can get their blue color from traces of titanium as well.
Stainless steel is a metal composed of iron alloy and a minimum of 10.5% of chromium. The chromium makes the metal resistant to staining, corroding, and oxidation. Stainless steel comes in many grades that determine the application of the metal. This is a relatively hard, durable, and affordable metal, which typically comes in light gray.