Ferrite rods also have a colour code, hence this article might be useful if you are recycling old parts and see a colour on the end of a ferrite rod. This is from my memory of repairing vintage radios, many years back. There were many different colour codes by many different manufacturers but the general rule of thumb was that the aerial input stage coils had blue markings, the high frequency stage coils had green markings, and the oscillator coils had red markings. This could be in the form of a dot, or a band, or just a splash of paint at the end.
Ferrite rod aerials also had colour markings, where the colour indicated the frequency band. This gave radio manufacturers the necessary information to build the proper coil with an appropriate tuning capacitor.