Gas Discharge Glow colours:

Hydrogen = Blue/violet
Helium = Pale salmon pink
Nitrogen = Pink/white
Oxygen = Blue/violet
Carbon dioxide = Blue/white
Neon = Red
Argon = Violet
Krypton = Lavender
Xenon = Blue
Water vapor = Pink
Butane = Green/red

*the first color is low pressure and the second is high pressure