Everything about Emerald totally explained
Emeralds are a variety of the
mineral beryl (Be
3Al
2(
SiO3)
6,) colored
green by trace amounts of
chromium and sometimes
vanadium. Beryl has a
hardness of 7.5 - 8 on the 10 point
Mohs scale of mineral hardness. Most emeralds are highly
included, so their brittleness (resistance to breakage) is classified as generally poor. The word "emerald" comes from
Latin smaragdus, via
Greek smaragdos, its original source being a
Semitic word or the
Sanskrit word,
marakata, meaning "emerald" or "green".
Properties determining value
Emeralds come in many shades of green and bluish green. There is a wide spectrum of clarity, dependent on the inclusions and fractures in the crystal. Clear stones with dark yet vibrant color command the highest prices. Almost all emeralds contain numerous flaws, cracks, and inclusions, which can negatively affect the clarity. These are given the name "jardin", from the French word for garden. The value of an emerald depends on cut, color, clarity, and
carat. Currently the best emeralds come from the Muzo mine in
Colombia.
Treatments
Most emeralds are oiled as part of the post
lapidary process, in order to improve their clarity.
Cedar oil, having a similar
refractive index, is often used in this generally accepted practice. The
U.S. Federal Trade Commission requires the disclosure of this treatment when a treated emerald is sold. The amount of oil entering an emerald microfissure is roughly equivalent to the size of a period (
full stop) in print. The use of green-tinted oil is generally not considered acceptable by the gem trade.
Emerald localities
Emeralds in antiquity were mined by the
Egyptians and in
Austria, as well as
Swat in northern
Pakistan.
A rare type of emerald known as a
trapiche emerald is occasionally found in the mines of
Colombia. A trapiche emerald exhibits a "star" pattern; it has raylike spokes of dark carbon impurities that give the emerald a
six-pointed radial pattern. It is named for the
trapiche, a grinding wheel used to process
sugarcane in the region. Colombian emeralds are generally the most prized due to their transparency and fire. Some of the most rare emeralds come from three main emerald mining areas in Colombia: Muzo, Coscuez, and Chivor. Fine emeralds are also found in other countries, such as
Zambia,
Brazil,
Zimbabwe,
Madagascar,
Pakistan,
India,
Afghanistan and
Russia. In the US, emeralds can be found in Gastonia,
North Carolina. In 1998, emeralds were discovered in the
Yukon Territory,
Canada.
Synthetic emerald
Emerald is a rare and valuable gemstone and, as such, it has provided the
incentive for developing synthetic emeralds. Both hydrothermal and
flux-growth synthetics have been produced, and a method has been developed for producing an emerald overgrowth on colorless beryl. The first commercially successful emerald synthesis process was that of
Carroll Chatham. Because Chatham's emeralds don't have any water and contain traces of vanadate, molybdenum and vanadium, a lithium vanadate flux process is probably involved. The other large producer of flux emeralds is
Pierre Gilson Sr., which has been on the market since 1964. Gilson's emeralds are usually grown on natural colorless beryl seeds which become coated on both sides. Growth occurs at the rate of 1 mm per month, a typical seven-month growth run producing emerald crystals of 7 mm of thickness (Nassau, K.
Gems Made By Man, 1980).
Hydrothermal synthetic emeralds have been attributed to
IG Farben, Nacken,
Tairus, and others, but the first satisfactory commercial product was that of
Johann Lechleitner of
Innsbruck,
Austria, which appeared on the market in the 1960s. These stones were initially sold under the names "Emerita" and "Symeralds", and they were grown as a thin layer of emerald on top of natural colorless beryl stones. Although not much is known about the original process, it's assumed that Leichleitner emeralds were grown in acid conditions. Later, from 1965 to 1970, the
Linde Division of
Union Carbide produced completely synthetic emeralds by hydrothermal synthesis. According to their patents (US3,567,642 and US3,567,643), acidic conditions are essential to prevent the chromium (which is used as the colorant) from precipitating. Also, it's important that the silicon containing nutrient be kept away from the other ingredients in order to prevent nucleation and confine growth to the seed crystals. Growth occurs by a diffusion-reaction process, assisted by convection. Typical growth conditions include pressures of 700-1400 bars at temperatures of 500 to 600 °C with a temperature gradient of 10 to 25 °C. Growth rates as fast as 1/3 mm per day can be attained
Luminescence in
ultraviolet light is considered a supplementary test when making a natural vs. synthetic determination, as many, but not all, natural emeralds are inert to
ultraviolet light. Many synthetics are also UV inert.
Synthetic emeralds are often referred to as "created", as their chemical and gemological composition is the same as their natural counterparts. The
U.S. Federal Trade Commission (FTC) has very strict regulations as to what can and what can't be called "synthetic" stone. The FTC says: "§ 23.23(c) It is unfair or deceptive to use the word "laboratory-grown," "laboratory-created," "[manufacturername]-created," or "synthetic" with the name of any natural stone to describe any industry product unless such industry product has essentially the same optical, physical, and chemical properties as the stone named."
Wispy veil-like inclusions are common in flux-grown synthetic emeralds.
Emerald in different cultures, and Emerald lore
Emerald is regarded as the traditional
birthstone for May, as well as the traditional gemstone for the
astrological signs of
Taurus,
Cancer and sometimes
Gemini. One of the more quaint anecdotes on emeralds was by the 16th century historian
Brantome, who referred to the many impressive emeralds the Spanish under
Cortez had brought back to Europe from Latin America. On one of Cortez most famous emeralds he'd the text engraved
Inter Natos Mulierum non sur-rexit mayor (Among them borne of woman there hath not arisen a greater Man. XI, 11) which referred to
John the Baptist. Brantome considered engraving such a beautiful and simple product of nature sacrilegious and considered this act the cause for Cortez loss of an extremely precious pearl (to which he dedicated a work
A beautiful and incomparable pearl) and even for the death of King
Charles IX who died soon after.
High Priest Breastplate
In
Exodus chapters 28 and 39, a number of precious stones are mentioned to be placed in the High Priest's Breastplate, representing the different tribes of Israel. This is generally considered to be (one of) the origin(s) of our present day tradition of
birthstones.
According to
Rebbenu Bachya, and the
King James Version, the
Hebrew word
Nofech in
Exodus 28:18 means
Emerald, and was the stone on the
Hoshen representing the
tribe of Judah. However, the
Septuagint translates the word as
Anthrax, meaning
coal, probably in reference to the colour of burning coal, and therefore many rabbinical sources, and most scholars, consider
Nofech to mean a red
garnet – traditionally called a
carbuncle, which happens to be the
Vulgate's translation of the word. There is a wide range of views among traditional sources about which tribe the stone refers to.
There are many complexities to identifying the Emerald as being the third stone or perhaps another stone on the breast plate. Multiple translations of the bible Further unreferenced claims regarding the possibility of what gemstone the Emerald could really have been include Jasper, and even
Rubies.
In some cultures, the emerald is the traditional gift for the 55th
wedding anniversary. It is also used as a 20th and 35th wedding anniversary stone.
Famous emeralds
Further Information
Get more info on 'Emerald'.
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