The Emerald owes its name to the Greek word « smaragdos » meaning Green Stone. The etymology of this name would possibly go back to ancient Persian or Hindi.
It is said to be sweet-looking and eye-easing.
All the fame of the Emerald is in its colour. The green of this precious stone is so beautiful that it can only be defined by its own name : Emerald Green.
With the Ruby, the Sapphire and the Diamond, the Emerald is one of the 4 precious stones. This stone belongs to the group of Beryls, like the Aquamarine and the Beryl. However, the Emerald is the noblest stone of this family.
History of the Emerald
In ancient times, there were many green stones called Emeralds.
The most ancient mines were located in Egypt and exploited around 2000 B.C. This is where the Emeralds found in the Pharaohs tombs were located. Afterwards, they were given a name : Cleopatra’s Mines. These mines were forgotten and rediscovered around 1816 by the French explorer Frederic Caillaud.
Nicknamed the « Green Monster Mountain », the deposit of Habachtal, Austria is located at an altitude of 2,200 metres in the national park of Hohe Tauern. It was known by the Celts and exploited by the Romans before falling into the custody of the Bishopric of Salzburg, and then the Duchy of Bavaria, which transmitted it to a Viennese jeweller who later sold it to the English.
In 1903, the British extracted 68,000 carats out of it which they had cut in India.
In 1975, a 49 carats Emerald was found and turned into a 10 carats stone, currently exhibited at the Museum of Natural History in Vienna.
Since day one, Emeralds from all origins were cut in India, which may have caused some confusion regarding the true origin of production.
The ancient mines of Ajmer have been exhausted but in 1943, new mines were discovered in the State of Rajasthan.
In the 19th century, in Siberia, in the Ural Mountains, deposits produced a great number of stones of various quality, some very nice, some very bright.
The biggest Emerald found in Russia weighed 101.25 carats.
Deposits and extraction of Emeralds
The Emerald is produced by the crystallisation of deep magmatic rocks. It is the slow cooling of this magma in fusion which is rich in iron, calcium, magnesium, fluoride and beryllium which favoured the formation of Emerald crystals.
Its deposits can be found in pegmatite veins or in the surroundings.
In Colombia, for this type of deposits only, the geological process was different. The constituent elements were pushed under great pressure through fissures called hydrothermal veins.
This allowed crystals to develop freely in a fluid environment, which led them to the acquisition of a perfect shape and great clarity. This process explains the existence of Emeralds which have the particularity to house water in the shape of a very small inclusion and a very small cubical crystal and a carbon bubble.
Its extraction is done almost exclusively in the Mother Rock where the Emerald was formed, in the small veins or along the walls of holes.
Deposits in Colombia
The biggest Emerald deposits are in Colombia. The famous mine of Muzo, located 100 km northwest of Bogota was already exploited by the Incas. It was abandoned and later exploited again during the 17th century. It’s this mine that gives the highly sought-after deep green quality stones.
Mining is done along open-air terraces. The Mother Rock is crumbly, soft and made of black limestone shale which allows for it to be easily detached with sticks.
Not too far away from Muzo, the mine of Coscuez, at an altitude of 1,200 meters has a smaller area but is more productive. It’s the 2nd biggest production of Emeralds in Colombia and its crystals are of an exceptional beauty.
One of the most impressive Emeralds is currently housed rough at the National Bank of Bogota and it weighs 1,759 carats (351.8 grams).
Very close to Muzo as well, the mine Pena Blanca is famed for its amazing Trapiche Emeralds discovered in 1964. It’s a one-of-a-kind formation, with a very thin hexagonal crystal at the centre, around which 6 other emerald prisms shine.
Trapiche Emerald :
At the Northeast of Bogota, Colombia, at an altitude of 2,300 meters, there’s another big deposit known as the mine of Chivor. It was first exploited by the Incas and then the Spanish until 1675, when it gradually became forgotten only to be discovered again at the beginning of the 20th century. The Mother Rock is made of a dark grey shale and grey limestone.
It’s in this mine that one of the biggest Emeralds in the world was found: the Emerald Patricia, 632 carats.
Other less important deposits have been found close to the mine of Chivor (including the one of Gachala).
Deposits in Brazil
There are several deposits in Brazil : the mines of Bahia, Goias and Minas Gerais.
Contrary to Colombia, the mines are in various states, scattered far from each other. They’re all privately owned. Brazil is the world’s second producer of Emeralds.
Northeast of Brasilia, in the State of Goias, an Emerald mine has been exploited since 1981 in the city of Santa Terezinha de Goias. It is the biggest supplier of Emeralds.
In the State of Gerais, southeast of Brasilia, the mine of Belmont was discovered by chance in 1978. The methods of extraction and techniques of production were mechanised and modernised to achieve Emerald production of very fine quality and colour.
The first Emeralds were found in 1913 in the mine of Salinaha, in the State of Bahia.
However, the biggest deposit in Brazil was discovered in Carnaiba in 1965. The Emeralds produced there are nicely coloured but have all sorts of inclusions which alter their clarity.
The biggest Crystal extracted from this mine weighed 6,225 carats (1,245 grams).
The first Emeralds discovered on the African continent were found in 1925 but exploitation only began in the fifties.
In South-Africa, in the province of Transvaal, two mines (Cobra and Gravelotte) produce only 5% of quality Emeralds.
Zambia is the main producer of Emeralds in Africa. In particular, the mines of Kufutu, Mufulira and Miku (exploited since 1978) produce Emeralds of really remarkable quality.
The mine of Sandawana in Zimbabwe was discovered in 1956 and is currently being exploited intensively. This deposit spreads over 35 acres. The shafts can go down to 200 meters deep and the galleries make a 50 kilometre-long network. It’s the 4th biggest Emerald producer in the world.
Other deposits are exploited in Tanzania and Mozambique.
Deposits in Madagascar
The mine of Ankadilalana, in the South-eastern part of the island, has been exploited since 1984. The stones have a lot of inclusions which affect their clarity. Their colour is similar to that of the Emeralds from Zambia.
Deposits in Pakistan
Since 1958, Emeralds have been extracted from the mine of Mingaora in the Swat valley.
Deposits in Afghanistan
In the Panchir valley, at the North of Kabul, the deposits there supply Emeralds of exceptional quality as prized as those of Colombia. The political climate in the region does not facilitate their commercialisation.
Various Emerald deposits in the world
In Australia, in Western Australia and most especially in New South Wales, the mines produce Emeralds of a pale green which is not prized on the market.
In the USA, in the states of North Carolina, Maine and Connecticut, the production is very low. However, nice specimens have been discovered :
- A 1,438 carats crystal was found in 1969 around Hiddenite, North Carolina ;
- A 1,276 carats crystal named Hiddenite Emerald as well as the 7.05 carats Emerald Shelby belong to the Smithsonian Institute in Washington D.C.
In Siberia, Russia, the biggest deposit is located close to the Takovaia River, in the Asian part of Ural.
Colour and properties of Emeralds
Just like Rubies and Sapphires, colour alone is not enough to guarantee the origin of the Emerald.
The crystals have a variable transparency and a characteristic colouration that goes from very light green or a soft green to very bright and intense green of quality stones in which a blue nuance can be seen.
Transparency only manifests in the stones of the best quality.
Chrome oxyde and vanadium are the substances linked to the colour of the Emerald.
The way the colour spreads itself is often uneven (streaks or areas).
The physical characteristics of Emeralds vary depending on their deposits of origin.
Heat can only modify the colour from around 700°C to 800°C. Emeralds are fragile because of the fissures created by internal tensions. They can only be heated in a cautious way and are not sensitive to chemicals, except fluoridric acid.
The hardness index of the Emerald is after that of the Diamond, Sapphire and Ruby (7.5 to 8 on MOHS’ 10-degree scale).
The brilliance of the Emerald is usually glassy. Inclusions are no longer considered defaults. If they do not take up too much space in the stone, they actually guarantee authenticity in comparison with synthetic stones or imitations. Professionals call these inclusions garden or frost.
The beauty of an Emerald is the result of a combination of the criteria of colour, intensity, homogeneity and limpidity.
Emeralds of Colombia
The Emeralds of Muzo are by far the most prized : their colour is intense, mellow, the green does not have too much blue or yellow in it. These stones have three-phased inclusions, which are characteristics of the three states of matter (solid, liquid and gas). These inclusions are made of a cavity filled with salt-saturated fossilised water which has a gas bubble that was formed during the cooling of the liquid (vaporisation) and a small cubical salt crystal (NaCl).
The Emeralds of Chivor are of a fine quality as well, of blue-green colour sometimes a bit light. The most common inclusions are made of yellow pyrite crystals (iron sulphur) whose metallic brilliance reflects light. Some can have three-phased inclusions.
Emeralds from Brazil
Emeralds coming from Brazil are rather frosty. They have a beautiful and quite intense green colour with some yellow to it that is organised in concentric parallel strips. They have a variable intensity following the hexagonal bases of the crystal ; the bottom can sometimes be colourless.
Emeralds can have unusual inclusions :
- Brownish mica sparkle inclusions (they do NOT EXISTS in Emeralds from Colombia) ;
- Inclusions of liquid-filled channels with numerous cracks more or less open, allowing impurities to infiltrate.
Emeralds from Africa
Emeralds from the deposit of Sandwana in Zimbabwe are usually small-sized, bright and of a very sweet and mellow green. They are very pure and have typical thin needle-shaped transparent inclusions in flexuous fibres (actinolite inclusions).
In Zambia, the Emeralds have a deep, blue-tinted green. They have some light frost of thin mica strips which do not alter the stone’s clarity.
Emeralds in Pakistan
The Emeralds produced are small-sized. The crystal is a limpid and bright yellow-tinted green.
Emeralds in Siberia
The Emeralds have a limpid and an intense blue-tinted green. They have carbon inclusions, small mica chips and actinolite needles either isolated or stacked.
The Cut of the Emerald
The hexagonal shape of the crystal inspired the octagonal Emerald Cut. By sawing the rough crystal in the middle and in the vertical sense, two rectangular-shaped crystals are formed, the dimensions of which are very close to the definitive shape.
The four corners of this rectangle are truncated and faceted so as to make the stone less vulnerable to shock. The cut is called a « sides cut off cut » or Emerald cut.
The step cut was created specifically for the Emerald because of its fragility.
The stones with the least transparency and the most inclusions often use a cabochon cut.