How do you apply Metal, Emeralds, and other effects on characters?

[Wulfbang Meow]

to be more specific, im asking if these effects can be applied to a single part of a character.

i know how to create an emerald texture, ive heard of metal effects being applied to a character, but im asking about a SECTION of a character.. say i wanted to give links shield a metallic texture or give it a texture that moves, but only have it apply to his shield and not the rest of him.. can we do that yet?