The long-standing fascination with emeralds may simply lie in their intense, radiant green color. Although rare in the gemology word, imperfections and inclusions are often tolerated in this beautiful stone, happily overlooked by many in exchange for the visual pleasure that this May birthstone brings. The bigger issue affecting the significant price and marketability of emeralds is the presence of a rich, dark green color.
Emeralds have a good hardness of 7.5 to 8 on the Mohs scale and belong to the large gemstone family of the beryls. Pure beryl is colorless. The colors do not occur until traces of another element are added. In the case of the emerald, it is mainly chromium and vanadium, concentrated (unusually) in different parts of the Earth’s crust. The tension created during this process produces some minor flaws in the stone – and some major ones. Only seldom is a large emerald with good color and transparency found, which is the primary reason emeralds are so valuable.
Rubies, sapphires and emeralds form the “big three” of colored stones, generating more economic activity than all other colored stones combined. In the last several years, the value of emeralds imported into the U.S. exceeded the value of rubies and sapphires combined.
Today, many emeralds are enhanced with colorless oils or resins. Although a common industry practice, it is done so with the caution of consequence, as these green treasures react very sensitively. While the hardness of emeralds protect it from scratches, its many fissures can make cutting, setting and cleaning rather difficult. When cutting takes place, the substances used or applied seals the fine pores in the surface of the gem. Removing them gives the stone a “matte” appearance. Emerald rings should also always be taken off before the wearer puts his or her hands in water containing cleansing agent and they cannot be cleaned in an ultrasonic bath.
A hard, but not tough stone, perhaps the lure of the emerald can be summed up by Roman Philosopher Pliny the Elder’s writing that “green gladdened the eye without tiring it.” True enough, the love affair with emeralds continues to evoke emotions in jewelry lovers everywhere.