Coinprism is, AKAIK, the first wallet implementation of the open-assets (colored coins) protocol: https://github.com/OpenAssets/open-assets-protocol/blob/master/specification.mediawiki. They mentioned earlier in this thread working on an add-on for bitcoin-qt in the future.
Colored coins are not centralized. For example, I could send colored coins from my Coinprism webwallet to a cold-storage address that I created offline. Your colored coins cannot be spent without your offline private key.
But you need to be very careful. If you import your colored coin cold private key into a non-color aware wallet you could accidently uncolor your coins. You'd have to go back to the issuer to ask for new colored coins and perhaps he'd give them you since you could prove that it was you who destroyed them.