There is in them a softer fire than the ruby, there is the brilliant purple of the amethyst, and the sea green of the emerald – all shining together in incredible union. Some by their splendor rival the colors of the painters, others the flame of burning sulphur or of fire quickened by oil. – Pliny, about the opal

Flowers that are so pathetic in their beauty, frail as the clouds, and in their coloring as gorgeous as the heavens, had through thousands of years been the heritage of children – honored as the jewelry of God…. – Thomas De Quincey

The opal resembles a fraction of the rainbow softened by a milky cloud. – Charles Blanc, Art in Ornament and Dress, 1875, translated from French