They don’t have any.
An object must be able interact with visible light waves in order to get a particular color. Violet has a wavelength of 380 nanometers. A hydrogen atom has a size of 0.1 nanometers. This is far smaller than the classical size of an electron or atomic nucleus.
This means that you won’t see any reflected light from visible colors when you shine light onto them. A shorter wavelength is required to capture images of small objects such as viruses. This can be done with an electron scanning microscope. Even smaller are atoms and molecules.
The frequency and energy are higher the shorter the wavelength. We would damage very small objects if we tried to use xrays to view them.