Serinium is tough, hard, scratch-resistant, and hypoallerginic. Serinium will never oxidize, tarnish, or lose color. Serinium is a bright silver-white color, nearer the color to Platinum than any other contemporary metal.
Colbalt is a silver-white color, similar to Platinum. Colbalt Chrome is less scratch-resistant than Serinium and Tungsten Carbide, but more scratch-resistant that Titanium, Stainless Steel, and precious metals. Cobalt is hypoallergenic.
Stainless Steel is harder than Silver and lightweight, but will easily scratch. Stainless Steel is significantly darker than White Gold, but still slightly whiter than Tungsten Carbide.
Titanium is lightweight, harder than Silver but much softer than Serinium, Cobalt, and Tunsten Carbide, so it scratches easily. It will not tarnish or break. Titanium is Hypoallergenic. Titanium is slightly lighter in color than Tungsten Carbide.
Tungsten Carbide is extremely scratch-resistant, heavy and hard, but brittle and susceptible to oxidation and accidental breakage. Tungsten Carbide is Hypoallergenic. Tungsten Carbide is a gray in color and can hold a polish until it oxidizes, which happens from exposure to air. When oxidized, it turns a dark, milky, gray-blue color. It is hard to polish to original state.
Zirconia Ceramic is extremely scratch-resistant, very light-weight and may crack or break easily. Zirconia Ceramic is available in many colors and solid in color, will not change or oxidize. Zirconia Ceramic is hypoallergenic.
***Information is from Jewelry Innovations