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

Do not judge from mere appearances; for the lift laughter that bubbles on the lip often mantles over the depths of sadness, and the serious look may be the sober veil that covers a divine peace and joy. The bosom can ache beneath diamond brooches; and many a blithe heart dances under coarse wool. – Edwin Hubbel Chapin

As though pure white snow flashed and sparkled with the color of bright ruddy wine, and was overcome by this radiance. – Author unknown, about opal

[T]he sapphire… is a concentration of azure. – Charles Blanc, Art in Ornament and Dress, 1875, translated from French