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

I prefer liberty to chains of diamonds. – Mary Worley Montagu

Many individuals have, like uncut diamonds, shining qualities beneath a rough exterior. – Juvenal