What colour was the gobstoppers in Charlie and the Chocolate Factory?

In "Charlie and the Chocolate Factory," gobstoppers are described as colorful, with a range of shades that include bright hues like blue, pink, yellow, and green. They are depicted as small, round candies that change colors as they are sucked on. The most notable aspect of the gobstoppers is that they can last for a very long time, making them a favorite among the children in the story.