“Rubies have their practical, as well as their beautiful aspects. . . . Primary among these is the use of the ruby for lasers, although I should say that natural rubies are of no use here—the key element chromium must be ‘doped up’ in synthetic rubies to create the laser. . . .
    The ruby laser was the first laser invented in 1960. . . . The key is chromium, that magic element that makes rubies red. Chromium atoms absorb green and blue light and emit or reflect only red light. Chromium is responsible for the ‘lasing’ behavior of the crystal.”

—Diane Morgan, Fire and Blood; Rubies in Myth, Magic, and History, 2008.