The hues of the opal, the light of the diamond, are not to be seen if the eye is too near. – Ralph Waldo Emerson

Now the melancholy God protect thee, and the tailor make thy garments of changeable taffeta, for thy mind is opal. – William Shakespeare, The Twelfth Night

[T]he hyacinth is like the tints of dawn passing from saffron to orange. – Charles Blanc, Art in Ornament and Dress, 1875, translated from French

[T]he diamond and other precious stones are focuses of light, and essences of colour which seem expressly created to ornament on a small scale the human body with all the splendours which adorn the universe on a large scale. – Charles Blanc, Art in Ornament and Dress, 1875