Soot from a smoky candle soft, black, opaque, so worthless it is wiped away as a nuisance. This is the element called carbon. The diamond in a queen's tiara - harder than any other natural substance, colorless, transparent, flashing with the brilliance of fresh dew, so costly it is worth king's ransom-this also is carbon, nothing more, nothing less. The difference between them is this: soot forms at ordinary temperature and pressure; diamonds at a temperature and pressure so high it is equivalent to that exists 150 miles below the earth's surface."

"The Mystique of Diamonds" A diamond is forever brochure.