How long have you had it? It is normal for corals to change colors while they settle in.
Different lights will color coral differently. For example, I can make forest fire glow under MH that LED cannot unless it is almost like a black light but they won't glow like at my house under 14K or 20K settings. This is normal too. T5s will have a different look as well.
Also, if you bought this coral from a reputable source, it might be forest fire. If you did not, then it could be forest fire look-a-like, which is never as good. We have all learned this lesson the hard way. Yours could be legit, but this will happen to you at some point where you probably got a knockoff.
Lastly, if it is growing and encrusting, then it is happy and will be as good as it can be in your tank soon. This is a great thing. Soon, you will be cussing how fast it grows and will sign a no-monti pact with yourself.