 Going up in value, sand we all know to be worthless, and gold is not a gemstone, so the diamond will obviously work (also making it that three is magic, an old belief common to fairy tales).That Serpentine's royal father's name means diamond is linking her proven royal heritage with the stone, as they are in the story, chronologically.The place of the mysterious bird, Constance, is unclear and seems to reflect another mythology or a related tale.