In its purest form the mineral beryl is colourless. The presence of impurities cause wonderful colours.
Blue beryl is aquamarine, green is emerald. Although not that well known, colourless beryl is known as goshenite.
Red beryl is exceptionally rare. Although once known as bixbite it's now known simply as red beryl. The name was removed due to possible confusion with another mineral with a similar name. Ironically the two were discovered by the same mineralogist.