Light-emitting diodes are made of special semiconductor compounds such as gallium arsenide (GaAs), gallium phosphide (GaP), gallium arsenide phosphide (GaAsP), silicon carbide (SiC), or indium gallium nitride (GaInN) all mixed together in different proportions to produce colors of different wavelengths.

Different LED compounds emit light in specific areas of the visible spectrum and therefore produce different levels of intensity. The exact choice of semiconductor material used will determine the total wavelength of photon emission and therefore the color of the emitted light.

The actual color of the light-emitting diode depends on the wavelength of the emitted light, which in turn depends on the actual semiconductor compound used to form the PN junction during the manufacturing process.

Therefore, the color of the light emitted by the LED is not determined by the color of the LED plastic bodies, although these plastic bodies are slightly colored to enhance the light output and indicate their color when they are not illuminated by the power supply.