Do dragons that act in opposition to their species alignment experience physical changes that reflect it?

Question

To clarify there are Chromatic Dragons which are always evil and Metallic Dragons which are always good but lets assume that a silver dragon started acting evil. Would the silver dragon have their scales lose their metallic hue or otherwise develop some sort of change that keeps the 'color coded for convenience' vibe dragons have going on?

Answer 1

No, or at least probably not

There is one possible exception, but that exception is described as unique. Otherwise, dragons who change alignment still continue to have the same color/biology that they always did.

Never as part of the game rules

I can’t back this up, really, since all I can really do is gesture at 50+ years of books and say “it’s not in there,” but, well, it’s not.

In particular, the latest edition of D&D has taken pains to emphasize that dragons are only “generally” their listed alignment, so a dragon not matching their color coding is allowed under the rules. Nothing says they will ever change into some other kind of dragon.

This isn’t actually a change, even though prior editions would use words like “always” for describing dragon alignment. For example, see our Q&A on dragon alignment in the “v.3.5 revised edition” of D&D. The latest version is just clearer about the existence of exceptions.

Once in a novel

The Dragonlance novel The Gully Dwarves (1996) focuses on a reformed green dragon, rejected by Takhisis, Verden Leafglow. Verden Leafglow took on a “verdigris” or “amber” hue, and was eventually “reborn” as a bronze dragon through the divine intervention of Reorx.

The divine interaction here is notable, and might suggest some things about dragon alignment in Dragonlance. In particular, the rejection by Takhisis happened first, which might suggest that if Takhisis hadn’t rejected Verden, Verden would have remained evil and green. Maybe. It’s not clearly indicated, that I can tell, and there aren’t any other Dragonlance instances we can really compare here. But we also don’t know if a nearly-thirty-year-old novel is even considered canon anymore; Dragonlance has been in a weird limbo for most of the time since due to the legal battles between Wizards of the Coast and Margaret Weis/Tracy Hickman.