What Determines the Color of a Translucent Object?

The absorbency of a material to different light wavelengths determines its color. Absorbed colors are absent from the transmitted and reflected spectra. The more a certain wavelength is absorbed, the less of it appears in the transmitted light.

Light scatters as it passes through a translucent material. This scattering adds randomness to the light waves passing through the material, causing them to emerge defocused from the other side. Translucent materials do not obey Snell’s law at a macroscopic level, usually due to the presence of interfaces within the bulk. At the atomic level, translucent materials absorb and reemit different wavelengths of light based on their electronic configuration, molecular vibration modes, chemical bonds and selection rules. Ultraviolet and visible light wavelengths are absorbed based on material bandgaps. Glasses do not usually have bandgaps corresponding to visible light, enabling them to transmit this portion of the electromagnetic spectrum efficiently.

Interatomic and intermolecular interactions determine absorption in the longer wavelength region of the spectrum. Infrared radiation induces a dipole moment in carbon dioxide, enabling it to absorb this portion of the electromagnetic spectrum and act as a greenhouse gas. No such induced dipole occurs in other molecular atmospheric gases, such as oxygen and nitrogen, which is why these gases do not contribute to the greenhouse effect.