The quote: "The secret of an opal's color lies not in its substance but in its absence." means that opal is so valuable because it is a symbol of hope and dreams. People have dreams that could be achieved by finding opal, and that gives them hope to keep on searching for it, even though they might have never found it yet. Hope and dreams are the "fuel" of humans that we need everyday to get out of bed. For the characters in the novel, opal was also a symbol of hope and dreams. But everyone has their own dreams, and for everyone the opal has a different meaning. For Ashmole it showed that believing is the most important thing. The opal showed Ashmole how dreams could be achieved by believing that they will happen. Ashmole wanted Kellyanne to get better and his dad to win the trial. The opal helped Ashmole to believe and hope that they will happpen. The opal is an important thing in the novel, because it was the only thing that gave the characters hope. I think that the different colors in the opal represented different dreams that people had. And the absence means that they only exist when you don't have them. If you got everything you ever wanted, you wouldn't have any dreams, and that would take the living out of your life. Living is having dreams and going after them and trying to achieve them, not the achieving itself.