AM has legal Yellow tint. Every State DOT law I am aware of makes blue an illegal color for lights on a street car if your not law enforcement.
Yellow is a legal color for FOG lites in 50 states. I don't think green is legal either, but I would have to check around. White, Yellow, and Red are legal only in certain uses.
White- Lights, driving lights, fogs.
Yellow- markers, front parking, driving lights (Sometimes) signals, fogs.
Red tail- Stop, and rear signal lights.
Grey tint slides by some enforcement as it just makes a dimmer version of the other colors; unless it get so dim you get a ticket for the (required) light not really being able to work; but fogs are not required so that would likely never happen on dark grey tinted fogs.