Depends on what it was exposed to. Think of the color in your corals like a sun burn. There are several degrees, each taking different times to heal and if severe enough can kill.
This isn't the only way to make things pop though. Painting the back glass of my tank black did amazing things for how I see my coral. Same can be said about the color spectrum from your tanks lights, where reds dull things up IMO
There are other things that can be done, but those are some general ideas without being too familiar with your system.
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