The Diamond, true king of gems, not content with its own inimitable purity, takes a pleasure, as it were, to assume in turns the proper colours of its subject-classes, and again to surpass each one in its own peculiar excellence.

The Natural History, Ancient and Modern, of Precious Stones and, Gems, and of the Precious Metals, Adamas (p. 60), Bell & Daldy. 1867