When I first see this quote, I was so confused. I checked some unknown words in this sentence,but it is not pretty useful. So I tried to find something connect with the book. It seems like every story has a thing that can be called hint keep appearing in the story, and all the plots happened around this hint. For example this opal, author needs to say story’s theme based on this opal. Opal is beautiful and colorful,but every one in this town eager to find the opal for changing to money. If it is not that valuable, no one tries so hard to find one. So everyone just likes opal’s value rather than opal’s appearance. That is what I understand this quote "The secret of an opal's color lies not in its substance but in its absences." in general.
    I think this opal run through the whole story, and it is also a symbol for every members in the family. Rex as a father is not a excellent father, at least he could not like other fathers that make much money. So from other’s view, he is a kind of loser, having not good relationship with his wife, becoming a ratter. Even Annie his wife sometimes looked at photos that with his exboyfriend, she must has a little bit regret, why I follow this man but not that rich man. Anyway Rex shows many bad sides to others, that is all his substance. However he finished all his daughter dream, for instance looking for Pobby and Dingan in the claim, holding a funeral for Pobby and Dingan. Rex took a heavy responsbility for her daughter and he never complained. That is his absence. Same as Annie, although she regrets, when Ashmol comes to her room, she hides those photos. This shows she does not want his child see her flimsy time. Ashmol looks young, so their parents never think about he is able to do something helpful for this family. The amazing part is he actually does much more things than anyone else to make kellyane better. He is begining to learn how to be a man.I think he knows Pobby and Dingan are not real, he still helps his sister find them and hold the funeral. He just thinks simple that he wants his siter feeling better. He deserved to get that sentence from Kellyane: You are the best brother. Kellyane has no firends in scholl, some children might think she is lonely and strange, but she lives happy when she spending the time with Pobby and Dingan. People think she is poor without any real friends. In fact it is the same, she has someone to care about to cherish. The only difference is others cannot see them.
    This small poor family seems easy to break, but they all have something shining inside of their nature which can save them. Change a word, how they show to others or how they act is not necessary important, what is amazing is their absences personalities must on the same track so that is valuable for the family.