Emerald is one of the most coveted gemstones in the world of jewelry. While we all know that this gem marks elegance and luxury in jewelry, few people actually know how it is produced. To learn more about the geological formation of this precious stone, Planetys informs you about the conditions of its formation and the main emerald mines in the world.
How is emerald formed?
Emerald is one of the four gemstones alongside diamond, ruby and sapphire. It is mainly used in the jewelry industry for the manufacture of luxury items such as those offered by Planetys. Hydrothermal in origin, it is formed under very specific geological conditions and requires great delicacy to extract.
Renowned for its deep green color, it is the noblest variety of the large beryl family. Sometimes cut into cabochons, the minerals of which it is composed are most often found in different parts of the earth’s crust.
A most surprising formation
Emerald is the result of the unlikely combination of two types of rock, one rich in chromium and the other in beryllium. Chromium, vanadium and iron are generally found in the earth’s mantle. Beryllium and alkalis, on the other hand, are found in the continental crust.
The alchemy takes place when magma (rich in potassium, aluminum and beryllium) intrudes into rock rich in iron, magnesium and chromium. Contact between these elements under favourable conditions gives rise to an emerald vein. Yet these elements are very different and chemically incompatible. The creation of these gems is therefore the result of a combination of exceptional circumstances, which explains their rarity and therefore their high price.
Emerald owes its incomparable green color to the presence of traces of vanadium and chromium in the beryl crystal lattice. Emerald, on the other hand, derives its structure from beryllium.
A natural peculiarity
A natural emerald has microfractures called inclusions that give it character. These impurities also make it one of the most fragile of gems. All these characteristics are in a way the crystal’s signature. Today, gemologists can determine an emerald’s origin by observing the nature of the stone and the foreign bodies that make it up.
It is very rare to find an emerald without inclusions. Inclusions are found even in the purest gems.
The main emerald deposits
The main sources of emerald production are Colombia, Zambia, Brazil and Russia. Others include Pakistan, Afghanistan, Zimbabwe, Ethiopia, South Africa and Madagascar.
Mining in Colombia
Colombia is without doubt the main source of this gem’s production, both in terms of volume and quality. The Incas exploited the first mines as far back as antiquity. However, these were abandoned with the decline of these civilizations. It wasn’t until the 16th century that they were rediscovered by the first Spanish settlers.
The main mining sites are located in the Boyoca green triangle, a valley in the Andes mountain range. The Chivor mine is in the south of the Boyaca department, the Muzo mine over 100 kilometers northwest of Bogotá and the Coscuez mine to the north of the latter.
Colombian gems are formed from sedimentary rocks called black shales, which are essentially composed of clay and organic matter. The finest emerald stones come from Colombian soil. They have an intense green color, sometimes with bluish reflections, and an incomparable brilliance. This stone is highly prized for its intense color and clarity.
Mining in Zambia
Mining is a recent phenomenon in Zambia. Today, however, it is one of the world’s largest producers. The first mine (Miku) was discovered in 1931. Today, it is the country’s 2nd largest mine. It has been in operation since 1978 and its stones can sometimes reach 130 carats.
These emeralds have unique, recognizable hues. They have a deep green color, with a blue tinge. This is why this treasure is so sought-after by jewelers the world over. Even if its color is less intense than that of Colombia, this crystal has a beautiful transparency.
The mines of Pakistan
The first gems were discovered in 1958 in the Swat district, a valley in the northern mountains of the country. It is difficult to make a clear and precise estimate of emerald resources in this land.
There are, however, some very fine gems to be found. The only drawback is that cut stones of more than two carats are rare.
The mines of Afghanistan
The mines are mainly located north of Kabul in the Pandjchir valley. Very elongated crystals are found in veins of quartz and albitic plagioclase, thanks to solid galleries cut into the mountain. Their appearance is often identified with that of Colombian emerald, as they feature the three-phase libellae characteristic of Colombian stones.
Some of this country’s gems are among the most beautiful on the planet. Those of the highest quality are perfectly crystallized and extremely clear. This emerald is highly sought-after by jewelry professionals, and its price can reach that of Colombian stones.
They can also reach significant weights. In 1985, a 190.5-carat crystal was discovered in Buzmal, a mining region located in carbonate rocks.
Mining in Ethiopia
Emerald mining is a very recent development in Ethiopia. In 2016, a deposit was discovered in the south of the country, 150 kilometers south of the town of Shakiso. Some are renowned for their extraordinary purity and brilliant green color.
What’s more, these stones are rich, saturated and beautifully crystallized. For all these reasons, they attract the attention of top jewelry professionals.
The mines of Russia
The first stones were discovered in 1830 in the Sverdlovsk region, known as Ekaterinburg, on the eastern side of the Urals. However, large-scale mining did not begin until the 1920s. At that time, the mines produced a large number of stones, but of fairly average quality. These stones were generally milky and very included, but they had nice dimensions.
Today, the site produces around 150 kg of excellent-quality ore every year. They can be recognized by their yellowish color. Some of the stones are very large, like the 1.54 kg emerald recovered from the mine in 2018 and the 1.6 kg emerald in 2019.
The mines of South Africa
South Africa is the leading producer on the African continent. The first mining sites were opened in the Transvaal region in the late 1920s. Like diamond and platinum mines, these sites are operated with large earth-moving equipment.
South African gems are rarely used in jewelry, due to their very average quality. Some fine specimens can be found, but only 5% of the rough extracted is of gem quality.
The mines of Zimbabwe
The first stones were discovered in this country in the late 1950s. The best-known mines are in the south of the country , in the Sandawana valley. Stones from this region are generally deep and warm in color, with shades of yellow. They are also very pure.
Their weight rarely exceeds 2 carats. They are therefore used as paving stones or calibrated for fine jewelry, as they lose a great deal of weight during cutting.
Madagascar mines
Madagascar produces emeralds of exceptional clarity, but with a color that differs from most people’s idea of an emerald. Their color is more akin to tourmaline. This is one of the reasons why these gems are rarely found on the jewelry market. It is also possible to find stones whose color is close to that of Zambian emerald.
