That is a state by state thing.....each state has different laws about plates and what can or cannot be used around them. (for expample, here in PA all plate covers and boarders are not allowed).
Quick googling found that the drivers handbook in FL requires a white light, so install purple at your own risk...
Florida Driverís Handbook - Your Vehicle
fwiw, I have 'super white' LEDs lighting my plate....they are similar to 5000K HID color