The emerald has probably been the May birthstone since the birthstone custom began--certainly ever since authorities started writing down official lists. It’s the quintessential gem of springtime, since it so strongly symbolizes life, especially of green and growing things. It represents regeneration and healing as well, and became the emblem of healing deities in many different cultures.
The symbolism in May's birthstone reflects time-honored qualities associated with the color green in many different cultures. Emerald is the gemstone that most seems to capture the magical quality of the life force--especially as manifested in fresh and verdant growth. It symbolized life and rebirth as well as love and fertility.
Among Muslims, emeralds represent the color of the Garden of Paradise. In the Vedic or sidereal astrology system of India, emerald and all green stones are assigned to Gemini and Virgo, and correspond to the 4th or Heart Chakra. Emeralds were once dedicated to Aphrodite/Venus--the Greek/Roman goddesses of love. It’s one of the best symbolic stones for romance.
Emerald’s name originally came from a Persian word that morphed into the Greek smaragdos, meaning green stone. Some changes over time in various Latin languages were esmaraldus, esmeraude, emeraude. In many germanic languages (German, Swedish, Danish, etc.), emerald is still known as smaragd.
In antiquity this was a word that originally meant all green gemstones, not just our May birthstone. Ruby and sapphire likewise come from words that originally referred to color, most likely because to the ancients, color was the most important characteristic of gemstones, linked to a tradition of color symbolism.
The Roman emperor, Nero, was said to have worn spectacles made of emerald in order to watch gladiator fights. The Romans (and other cultures) believed that emeralds were healing and soothing to the eyes. The spectacles may have done more than protect Nero’s eyes from the sun. They may have been fitted with carved magnifying lenses to improve Nero’s vision (described as weak). Lenses were widely used in antiquity (one known as the Nimrud lens is 3,000 years old).
However, Nero’s lenses were probably not actual emeralds, because specimens big enough and transparent enough to carve into spectacles were (and still are) extremely rare. They were likely made of another kind of smaragdos.
Umina, which means “emerald” in the indigenous language of Peru, was a goddess of health. In a temple in Manta, Peru, the goddess was embodied by an emerald said to be the size of an ostrich egg or a melon. It was cut in the shape of a torso, with breasts and a half-human face. To heal the sick, priests rubbed a soft white cloth on the emerald idol, which they applied to the patient.
Umina’s favorite tribute (or perhaps that of her priests) was said to be other, smaller, emeralds (her “daughters”). The temple was raided by Spanish invaders and all the “daughter emeralds” were seized by them. However the goddess stone mysteriously disappeared, and was never seen again.
It’s said that temple priests managed to hide it, but it could just as easily have been secreted away by a Spaniard, or even nicked by a non-clergy Peruvian. In any case, Umina wasn’t the first nor the last priceless gemstone ever to disappear under mysterious circumstances.
Enormous quantities of emeralds were stolen by Spanish conquistadors in the 16th-17th century. Most were sold to the three Islamic kingdoms of that time (Turkish, Persian and Indian). The color green has great significance in Islamic culture, and emeralds were highly prized. Emeralds of the Mughal empire in India were often cut as talismans in a flat rectangular shape, and carved with religious inscriptions.
Emeralds have more flaws (inclusions) than any other gemstone; in fact, this became one of its defining characteristics.
Emerald connoisseurs prize clarity in emeralds, but at the same time develop an appreciation for its flaws, referring to inclusions and fractures as gardens (jardin) and scenery, complete with moss, ferns, leaves and flowers, reinforcing emerald’s association with vegetation and growth.
Some jardin are more beautiful than others, which may significantly affect price. But also, inclusions and fractures can distinguish emeralds from other green gemstones, and may also identify where an emerald was mined. For example, an emerald primarily colored by chromium, with pyrite inclusions and tiny cavities filled with gas, sea water or salt crystals point towards Colombia as the stone’s origin.
It’s standard practice to treat most emeralds by filling fractures where they reach the surface. The traditional filling is natural cedar oil, which has a refractive index similar to emeralds. In other words the oil bends light in almost the same way, blending with the stone, so the flaws become much less noticeable.
Since this isn’t a permanent treatment, synthetic fillers are now often substituted for cedar oil. Though filling is an accepted practice, the fillers should not be dyed and the extent of filling should be disclosed so that emeralds can be graded as accurately as possible.
Colombian emeralds are the traditional favorites, but May's birthstone is also found in Brazil and Zambia. Zambian emeralds are known to have much fewer flaws, but have darker (often bluish) tones that result from vanadium, its main coloring component. Often less costly, they are favored by those who don’t like jardin and want fancy shapes and cuts traditionally not used for emeralds.
To preserve the treatments, it’s important not to clean emeralds in hot water, steam or ultrasonic cleaner machines. Simply use a soft brush and gentle soap, then rinse with cool water. Despite its hardness (7.5+), due to its inclusions emeralds should be treated with care.
The emerald is the only gemstone that has a special cutting style named after it. The “emerald cut” was designed to avoid stressing the often-fissured and thereby brittle stone, while featuring its beautiful color and luster. As shown in the diagram below, the emerald cut has a large table (central flat area) for viewing color, and the corners are cut away to prevent chipping.