The emerald is often considered one of the most valuable of the coloured gems and with good reason. The brilliance of their green hue is often enough to add a stunning dimension to any piece of jewellery, and the respect with which they have been treated for centuries is proof of the beauty and worth of the mineral gem.

Characteristics
Emeralds, which derive their name from the Greek term smaragdos, meaning green, are a green variety of the mineral beryl, which comprises of, among other things, silica and aluminium. Beryl gems are characterised by their solidity, relatively light weight, and resistance to acids, and usually occur in six-sided prisms. Like all coloured gems, the value of an emerald is determined by its colour, cut, carat and clarity.

Beryl is in itself a colourless mineral, and the radiant green colour of emeralds comes from trace amounts of chromium or vanadium that may be present in it. Colour is perhaps the most important factor in determining the value of an emerald. Prized emeralds are usually deep coloured or well saturated, and range from dark to light greens.

The gem is also rarely unblemished. Almost every emerald contains flaws known as inclusions, and a small amount of inclusions are customary without reducing the value of the gem. In fact, some buyers prefer to purchase emeralds with inclusions rather than perfectly clean ones as the inclusions, which occur naturally, are a mark of genuineness. The inclusions are sometimes referred to as jardin or garden, and are considered natural features of the emerald. Fine inclusions that do not mar the appearance or colour of the emerald are usually acceptable.

While cutting and shaping emeralds, cutters must be cautious to prevent them from breaking if the inclusions are deep or considerable in number. This has given rise to the "emerald cut" - a rectangular or square cut with bevelled corners to protect the emerald without detracting from its beauty. Emeralds are also cut in other shapes such as marquise, round, oval or pear, and stones that have several inclusions may be cut into rounded cabochons.

Emeralds around the World
Colombia: The emeralds of the South American country of Colombia are reputed to be finest in the world. The Cordillera Oriental mountain range of the Andes holds what is known as the 'Emerald Belt', where the leading emerald mines are located. The Muzo and Cosquez regions, located at the northwest end of the belt, and the Chivor region, located at the southeast end of the belt, are the principal mining regions of Colombia. The Muzo mines, located on the banks of the River Mineró, are the most famed emerald mines in the world.

Colombian emeralds are valued for their rich, dark hue, and often have light inclusions. The Muzo emeralds are often described as being 'Muzo Green', while the Chivor emeralds tend to be a dark green with overtones of blue. Colombia is also famous for the Trapiche, a rare type of emerald that resembles a star, and has been found in the Muzo, Peña Blanca, Chivor and Cosquez mines. In the Trapiche emerald, inclusions of albite and quartz, among others, extend in the form of spokes and divide the emerald, giving it a star-like shape.

Zambia: The emerald mines of Zambia also produce gems of exceptional quality, which are usually darker than those from Colombia and with fewer inclusions. Zambian emeralds are popular for their clarity and tend to have more blue or grey overtones than Colombian emeralds, which could be a result of traces of vanadium in the gem. Zambia, along with Zimbabwe, is a major source of the gem on the African continent.

Brazil: The Brazilian mine, Nova Era, is also steadily gaining a reputation for producing quality emeralds. These contain more inclusions than Colombian emeralds but are no less stunning. Brazil is one of the largest producers of commercial emeralds, and the country's mines yield stones that are relatively large.

Afghanistan: In South Asia, it is Afghanistan's Panjsher Valley that dominates the emerald trade. The region has been marked by turmoil and strife for decades, but is relatively untouched due to the ruggedness of its terrain, both of which are factors that have protected the emerald mines of the country.

The mines are located high up the mountains east of the Panjsher River. The Buzmal mines in Bismal-Riwat are the oldest known emerald mines in the country and are also relatively perilous because of the dangerous methods adopted by the miners. The Mikeni mines are at a high elevation and are relatively untapped because of their proximity to a land-mine field. Despite these factors, and the severe weather conditions and harsh territory of the mountains, workers still search for emeralds in the mines of the Panjsher Valley because of the spectacular gems that it produces.

Local miners believe that the Mikeni and Darkhenj mines contain the most beautiful emeralds in the region. Panjsher Valley emeralds range in colour from pale to very dark green and are said to rival those of the Muzo mines in splendour and quality.

History of Emeralds
The first known emeralds were believed to be mined near the Red Sea in Egypt. Archaeologists discovered mines that were already depleted by the 19th century, and as early as the 13th century, Mohammed Ben Mansur described emeralds as "belonging to the kingdom of Egypt", but it is believed that emeralds were in existence thousands of years ago as several ancient mummies have been found adorned in jewels made of emeralds. The Egyptian emerald mines were also referred to by ancient historians like Strabo, Diodorus, and Agatharchides, and Cleopatra is said to have had affection for the gem. Perhaps the foremost emerald mine is that in the mountain valley of Wadi Sikait in the Egyptian deserts, which the Romans referred to as Mons Smaragdus, meaning Emerald Mountain. It is believed that mining in this region began as early as the fourth century B.C.

Romans too seemed to be enamoured of the emerald. The gem has been discovered in the ruins of Pompeii and Herculaneum, and the Emperor Nero is fabled to have used an emerald as an eye-glass.

A famous legend tells of the Manka Valley in Peru, where there existed an emerald the size of an ostrich egg that the Incas treated with great reverence. The gem was regarded as the Goddess of Emeralds, and priests displayed it to the public only during festivals and celebrations. The Incas, Aztecs, and other ancient civilisations are widely believed to have had great amounts of emerald jewellery for themselves and loose emeralds to offer to the Gods.

One of the world's largest emeralds, the Mogul Emerald is among several to have belonged to the Mughal Emperor Shah Jahan. The emerald, which dates to 1695, weighs 217.8 carats and is 10 cm tall, is inscribed with sacred scriptures on one side and floral motifs on the other.

Famous Emeralds
Caravel Pendant: The Hermitage Museum in Russia is home to one of the finest specimens of carved emeralds ever created. The Spanish pendant, which dates back to the late 16th century, is in the shape of a caravel and is made entirely of emeralds and gold. The base of the caravel consists of a single transparent emerald of a deep green hue, while the sail and cross is also made of emeralds. The pendant is considered one of the Hermitage's most prized pieces of jewellery.

Patricia Emerald: The 632 carat Patricia Emerald is considered to be one of the greatest emeralds ever discovered. The stone, which was found in the Chivor Mines, is named after the daughter of the mine owner. What makes this emerald exceptional is that while most uncut emeralds have six sides, the Patricia Emerald is twelve sided or dihexagonal. It is both a large and extremely well formed stone, and is one of the few emeralds of its size and quality that have been preserved uncut. The stone is now on display at the American Museum of Natural History.

Unnamed Carved Emerald: On display in the Smithsonian National Museum of Natural History is an unnamed cabochon, a beautiful specimen of the gemstone. The emerald, which was found as a rough stone in Colombia, is carved in the shape of a woman's head, with the pyrite, or fool's gold, crystals that occurred naturally within the emerald forming the woman's hair and earring.

Caring for Emeralds
The emerald is a durable stone, not very susceptible to scratches, but it is easily chipped. Modern emeralds are often treated with natural, colourless oils or resins to conceal inclusions, and therefore appropriate care must be taken of the gems.

Emerald rings must never be worn while washing hands or using any detergent. The stone must also not be washed with soap or steam or be cleaned with an ultrasonic cleaner, as it will result in removing the oils and the flaws that the oil was used to conceal will become visible.

Emeralds may be cleaned by using extremely mild dish soap and warm water solution, and something extremely soft, like a worn-out toothbrush. It is also recommended that emeralds are not left immersed in the solution and that they are patted dry.