Facts about Emeralds

Facts about Emeralds

One of the most popular and attractive gemstones, emeralds are acknowledged as a sign of prosperity, loyalty, friendship, and a high standard of living. In a geological sense, this gemstone belongs to the Beryl family. Sometimes, the green-colored specimens are valued more than diamonds, especially the flawless ones. This CrystalBenefits article gives you a good number of interesting facts about emeralds.
Green Glares
Following philosopher Pliny's advice, the Roman emperor Nero wore emerald sunglasses to calm his eyes, while watching the gladiators fight.

The word Emerald has been derived from a Latin variant of the Greek term Smaragdus, which means 'Green Stone'. It is the birthstone of May. This gemstone mostly occurs with some flaws, inclusions, and minor defects. Obtaining a clear flawless emerald is very rare. Rather, many people prefer such flaws in the gem as they confirm the gemstone's authenticity. The deeper its color, the higher its value. The emerald is a part of the famous group of four gemstones, which includes diamond, ruby, and sapphire, as the other three members. Let's look at some interesting facts about this brilliant gemstone - the emerald.
History
According to records, Egyptians were the first ones to mine emeralds. The Cleopatra mines are the oldest ones with reference to this gemstone. These mines were rediscovered in the early 19th century, and according to archeological studies, they consisted of massive reserves of emeralds. They were also a major source of emeralds in that region, as an extensive trade of emeralds took place between Egypt and the nearby European countries. These mines were used for more than 3000 years.

In the 16th century, Spanish conquistadors started conquering the northern South American regions, especially in Colombia. They discovered that the native tribes wore shiny green gemstones as a part of their jewelry. They started exploring the Inca regions, and after about half a century, they forced out the natives and took control over the Colombian emerald mines. Currently, emeralds from Colombia are considered to be one of the finest ones in the world.

When India was under the Mogul rule, extensive trading of emeralds took place especially in the 17th and 18th centuries. The Moguls wore emerald jewelry for good luck and prosperity. These rulers set up their base mostly in the western part of India, and hence, trade flourished mainly in the states of Rajasthan and Gujarat. They also carved prayers on emerald tablets, and preserved them for years. Such specimens can still be found in archeological excavations, and a famous example of such tablets is:

The largest inscribed emerald in the world is the Mogul Mughal Emerald. Weighing more than 200 carats, this Indian artifact dates back to the time of Aurangzeb, and it consists of a Shi'a Muslim prayer in naskh script, inscribed on its front side. In 2001, it was sold at an auction for a mind-boggling USD 2.2 million!
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Properties
Properties like gem color, weight in carats, the type of cut, and clarity, determine the gemstone quality. The emerald's green color occurs typically due to trace amounts of chromium and vanadium present in this gemstone. It belongs to the Beryl family, which has other gems like aquamarine, heliodor, golden emerald, red emerald (bixbite), etc. as its members. The scientific formula of beryl is:

Be3Al2(SiO3)6 (aluminum beryllium silicate)

▸ This mineral shows a hardness of 7.5 - 8 on the Mohs scale of hardness.

▸ It belongs to the Hexagonal crystal system, and is included under the low toughness category of gemstones due to high occurrence of flaws, fractures, and inclusions.

▸ Emeralds may develop internal cracks if banged hard, or if subjected to extreme temperature change.

▸ They are one of the softest gemstones known to man.

▸ The color of emeralds varies from greenish-blue to greenish-yellow, with intermittent shades of blue. Appearance-wise, bluish emeralds are frequently mistaken as aquamarines.

▸ Emeralds are usually in the form of an Oval cut or the rectangular topside-faceted Emerald cut.

▸ The clarity of this gemstone is judged according to the visibility of inclusions (foreign mineral particles) in its interior, and also, by the nature of cracks or fractures on its surface. Such inclusions are known as jardin, derived from a French term which means 'garden'.

▸ Trapped air bubbles, different mineral fragments, hairline fractures, opaque materials, etc., are some examples of the defects present in the stones.

▸ These flaws are unique and different in every specimen, i.e., no two specimens can be the same. Some rare ones do not show any visible inclusions, and hence, are known as flawless emeralds.
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Formation
Emeralds are formed in all three types of rocks: igneous, metamorphic, and sedimentary. The main constituents of these gemstones are beryllium, aluminum, and traces of chromium and vanadium. All these elements are found on the Earth's crust. When the formation of new crust takes place, the molten magma rises upwards, and carries the chromium and vanadium elements to the surface.

Igneous Rocks
In the igneous rocks, emeralds are formed due to hydrothermal processes, mostly in granites and pegmatites. Groundwater carries many dissolved minerals including beryllium, aluminum, silicon, etc. When this water comes in contact with molten magma, it gets superheated, and elements like chromium and vanadium can get mixed with it. Due to generation of steam, the water starts rising upwards, and enters the cracks and fissures in igneous rocks like granite, basalt, diorite, etc. During cooling and solidification, as the water passes through the cracks, the minerals get deposited along the walls resulting in hydrothermal alteration of the host rock. In specific and favorable conditions, emerald formation takes place along the fissure walls and cavities along with other natural impurities. This is known as the hydrothermal process of mineral formation, and it occurs mostly in near-surface rocks like granite and gabbro. Pegamtites mainly are plutonic and hypabassal igneous rocks, i.e., they are found deep beneath the Earth's crust. In this case, molten magma directly comes in contact with the rocks, and enters the cracks and fractures. During the process of subsequent cooling and magma solidification, the cracks are filled with newly formed minerals, and the dissolved elements are precipitated in the remaining magmatic fluid. Under favorable conditions, elements like chromium and beryllium get deposited to form large emerald crystals.

Sedimentary Rocks
In case of sedimentary rocks, emerald formation is in a detrital manner. The host rocks are formed after continuous erosion of parent rocks, resulting in minute mineral fragments. These particles are transported over long distances, and get deposited in areas that show basin-like or depression-like geomorphic features. The water involved in transportation also carries dissolved elements like chromium, beryllium, vanadium, etc. In particular conditions, these elements are deposited, thereby forming emeralds in the form of sediments, which are compacted over thousands of years due to high pressure of the overlying materials. The main examples of sedimentary rocks showing emerald deposits are shale, calcite, limestone, etc.

Metamorphic Rocks
Metamorphic rocks are formed as a result of changes in pressure and temperature of the surrounding environment of the parent igneous or sedimentary rocks. These changes may be due to tectonic activities, volcanic eruptions, crustal upheavals, etc. In such rocks, the original mineral composition and structural habit completely changes, and there arises a possibility of the formation of new fractures, cracks, or joints. Such features might be intruded by molten magma, or acted upon by hydrothermal processes, resulting in mineral deposition and precipitation of certain elements. Under favorable conditions, if beryllium, chromium, and vanadium are deposited, emerald crystals are formed.

Synthetic Emeralds
Recent technology has also made it possible to artificially create or 'manufacture' emeralds in laboratories. This involves using several chemicals and solutions, which provide the necessary ingredients for gemstone formation. In this process, a seed crystal of a mineral is used, which acts as a nucleus. Around this crystal, specific elements in the form of solutions are precipitated to make the gemstone. These artificially created gems are also known as synthetic emeralds, and basically, they are of two types: hydrothermal and flux-growth. The former consists of depositing certain chemical solutions around a beryl seed crystal, in an acidic and silicon-rich environment. The latter consists of the application of a flux, which is composed of tungstates, molybdates, and vanadates, around a beryl seed crystal. An artificial melt is created, and the seed crystal is rotated in this melt. Slowly, the gemstone is formed.
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Methods of Treatment
▸ Most of the commercially mined emeralds are subjected to certain treatment procedures, mainly to decrease the inclusions and fractures, increase their attractiveness, and to make them as less fragile as possible.

▸ Immersion in oil results in filling up of cracks and fissures, forming a less flawed, or even a visibly flawless emerald. For example, cedar oil, synthetic oil, and polymers like Opticon are mainly used in these methods.

▸ Sometimes, epoxy-resins are also utilized to treat the fractures, and this technique increases the gemstone's transparency.

▸ Another method consists of using green-tinted or colored oil, but this imparts an artificial look to the gem. Hence, impure and low-quality emeralds might be treated in this manner, to make them appear rich and vivid green in color, ultimately fooling the customer. Hence, it should be confirmed with the jewelers, whether the gems have been treated in this manner or not, before purchasing them.

▸ Heat and steam treatment is also done in some cases, but it should be avoided, as heat can cause widening of existing cracks, and even formation of new fractures. This might cause the gemstone to shatter and break.

▸ Also, the filler materials like polymers and oil might seep out, causing the gem to break.

▸ Subjection to ultrasonic techniques tends to remove some inclusions and impurities, but overdoing it might have some unwanted effects on the stability and strength of emeralds.

▸ The above-mentioned methods only serve to increase gemstone clarity. Some of these techniques are not allowed in some parts of the world (for example, usage of green-tinted oil is mostly not done in the United States).

▸ Jewelers should take utmost precautions and care while cutting and polishing the gemstones, so as to avoid damage.
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Distribution
▸ In ancient times, Egypt was the center-point for mining of emeralds and their trading.

▸ This gemstone is also being mined since many centuries from Austria and India.

▸ Today, the largest and some of the most valuable emerald deposits are found in Colombia. The Gachala emerald found in Colombia in 1967 weighs 858 carats, and is among the world's largest and most famous emeralds. It was named after the town of Gachala, where it was found. The major emerald mines of this country are located in Chivor and Muzo. These deposits consist of more than 50% of the total emerald reserves of the entire world.

▸ A recent study has found out that between 2001 and 2010, the production of emeralds in Colombia has increased by about 80%.

▸ Zambia is second in the list for production of emeralds. It accounts for about 20% of the global deposits of this gemstone.

▸ Deposits are also found in other countries like the United States, India, Australia, Brazil, Russia, etc.

▸ The emerald mines of North Carolina in the United States, are quite famous for these beautiful gemstones. This area is the only emerald mine in the U.S., which is open to public for visits.

▸ In Brazil, the Bahia and Minas Gerais mines are famous for inclusion-free and yellow-tinged emeralds. Also, rare occurrences of the emerald cat's eye specimens have been reported from this area.

▸ In South Africa, these gems are found in the Transvaal regions. The Somerset mines produce emeralds of excellent quality.

▸ In Zimbabwe, the Sandwana mine has medium-quality emeralds, whereas in Russia, in the Ural mountain region, these gems are found to have a light-colored and dull appearance.
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Uses
▸ Emerald stones set in silver rings are still quite popular. Many emerald necklaces and pendants are also made. Such necklaces have been quite popular in British history, especially with the British Royalty.

▸ Emeralds were also used as good luck talismans, and to keep away bad and negative spirits. They are said to induce peace and calm, and were also believed to cure epilepsy.

▸ These gems are used in astrology, mainly to foretell the future, and have been given symbolic meanings. It is believed that emeralds increase love, loyalty, friendship, and caring qualities in people who carry or wear them in any form.

▸ Emeralds have been attributed with healing powers, and also with the abilities to soothe the mind and increase intelligence levels in people.
Conserve the Green Stone!
Although emeralds are greatly venerated all over the world, they have been mined extensively, especially in the last century. This has resulted in some of the mineral reserves getting depleted. Synthetic emeralds may be similar in appearance to the natural ones, but they certainly lack originality. With the use of synthetic emeralds, the world may not feel a shortage of this gem even if the reserves decrease. But once the natural is exhausted, we won't have any option, but to be satisfied with the artificial. Thus, the conservation of not just emeralds or gemstones, but mineral deposits at large, is of utmost importance.