Hydrogen has signature colors that appear when the atoms are excited. This image from NASA-Ames shows a hydrogen arc lamp fluorescing:
Neils Bohr used the emission spectra of hydrogen to develop his model of the atom. In short, quantized energy levels release specific bands of light with unique colors. A description of the physics is here. Here are the corresponding colors and electron transitions:
I used this handy converter to go from emission wavelength to RGB color code.