May's birthstone is the emerald. This gem appears in a magnificent range of greens, the darker containing blue and the lighter containing yellow. Because most emeralds are found with surface cracks, it is accepted practice to oil the gem to fill in the cracks and improve the gem's luster. While this is a relatively new practice, this kind of attention devoted to the emerald is not new.
In the Middle Ages, jewelry enthusiasts wrote lapidariums, or special books devoted to gems, including emeralds. A good emerald was believed to be “greener than any green that lay next to it.” Emeralds were also believed to hold special powers. Raymond Lull wrote of experiences in which he witnessed emeralds easing the suffering of the sick.
Of course, along with emeralds themselves, emerald jewelry has always been treasured, especially by the elite, starting long before the Middle Ages. Cleopatra, the famous Queen of Egypt, loved her emerald necklaces. Marlene Dietrich, one of the queens of black and white Hollywood, loved all emerald jewelry. And even today, the stars of Hollywood are seen walking the red carpet and wearing emerald necklaces and emerald earrings.