Re-chroming them, or just paint work?

There are a few chrome shops who will replate emblems.

Painting can be done at home. If the background is painted you spray the whole emblem. After it dries come back with a cloth that is barely damp with carb cleaner wrapped tight around a popsicle stick and lightly polish the top surface until you rub thru the paint to expose the chrome again.

It's not a fast process, but if take your time they will look great when done.