Anodized finish, yes? It's not unheard of to re-anodize, but there are significant caveats to re-doing it because anodizing bonds with the aluminum and to redo it the old anodizing has to be blasted off, which takes metal with it and can affect dimensions.

I agree with s&wchad that S&W won't do it, and a place that will needs to have an excellent reputation working specifically with firearms. It'll significantly increase what you paid for the firearm while likely adding nothing to its monetary value, if not diminishing it.

What's your intention with the gun? If it's going to be a worker, I'd clean it, maintain it and leave things be. If you want easy added protection, Cerakote or something similar. But it's uncommon that it's worth re-anodizing a firearm, I think.

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