Tourmaline appears to change color depending on how much light is shining through it or onto it. It only takes a slight change in the composition for the colors to change completely.
Tourmaline can be found in a wide variety of colors. You will find tourmaline that is red, pink, orange, yellow, green, blue, purple, white, brown, grey, or black. Favorites in this variety are tourmaline having multiple colors present in one stone.
You can find out if your tourmaline is genuine by examining it under artificial light. It needs to be a bright artificial light, and you'll observe genuine tourmaline changing color.
Pink tourmaline has a brownish undertone when under artificial light. If you do not see this brownish undertone, then you are most likely dealing with a fake gemstone.