All the items look pretty good, but there's not enough contrast going on with them. When you're dealing with shiny/metallic/gem-like surfaces, try to get as much contrast going on as possible; white looks much brighter next to black or near-black than it does next to the light silver you have for the body of your ring, for example. Since the gray is already so bright, it makes the white highlights look less brilliant than they should by comparison. Here's a quick recolor of the objects I did for you.
