Tungsten Carbide is a rare metal found naturally on earth, and is one of the hardest metals on the planet. It is 10x harder than gold, and therefore it does not bend or get distorted with time. It is also one of the most scratch resistant metals. However, please keep in mind that tungsten rings can shatter when enough force is applied, or it drops on hard surface.
Tungsten naturally is a dense metal, and therefore feels luxurious and heavy when worn. If you have certain allergic reactions towards some metals, then this is the perfect choice, as it is naturally hypoallergenic.