From Gem Society
Although emeralds occur in many localities, some sources are better known for high-quality gems than others. Learn about famous (and not so famous) emerald sources, from ancient times to the present day, and how to identify emerald origins.
People have treasured emeralds throughout human history. Indeed, emerald exploitation and trade have influenced wars and conquests. Of course, the premier sources of emeralds have changed over time.
Before the start of mining at the now-classic Colombian sources, most emeralds came out of Egypt. Deep in the desert, people began intermittently mining the Egyptian emerald deposit around 500 BCE. Later, during Cleopatra’s reign (51 BCE-21 BCE), mining became a more regular activity. She especially favored emeralds and took every occasion to flaunt her wealth in emeralds. As a result of increased demand, a town was built near the mines around 30 BCE to provide protection and cater to the miners’ needs.
Although these emeralds were often either opaque or translucent and generally pale in color, Egypt became the premier source for these gems. They also became highly prized jewelry stones in the Roman Empire. Most emeralds were left in their original hexagonal crystalline shape, often with a hole drilled through along their length for use as a bead, but some were polished into rounded beads or cabochons.
Cleopatra’s emerald mines have long since run dry. Although they were re-discovered in the 1800s, further efforts to extract emeralds have proven unprofitable. Due to the extreme conditions, the difficult-to-reach deposits, and the less-than-stellar quality of the emeralds, these mines remain closed.
In addition to Egypt, sources in Austria, India, and Central Asia may have been exploited prior to 1000 CE. However, these constituted only a small portion of worldwide emerald production. The most well-known of emerald origins remained Egypt — until the Spanish conquest of the Americas.
Mining at the now-famous emerald mines at Chivor, Colombia began in the 11th century CE. By the time Columbus arrived, emeralds had long since traveled as far north as Mexico and south into Chile and Peru due to extensive trade routes between the Incan, Mayan, and Aztec civilizations. Not surprisingly, these glowing green gems became a part of religious ceremonies and were even a form of currency in these lands.
Not long after their arrival, the Spaniards quickly took control of gold as well as emerald mines in the Americas. Beginning in the early 1500s, Spanish ships would bring massive wealth to Spain. These gems spread throughout the world, and Colombia quickly became the most desirable of emerald origins. In fact, many famous emeralds came out of these historic mines.
More recently, Brazil and Zambia have become important emerald origins. However, the quality of these emeralds is generally poorer than those from Colombia, which remains the premier source for emeralds.
In 2016, the discovery of an emerald deposit in Ethiopia took the gem world by surprise. Many emeralds from this source have excellent color and even better clarity than most from Colombia. As a result, these emeralds command a slight premium in the market.
Because emerald origins can impact price, gemologists must be able to identify an emerald’s source country. In order to gather clues, gemologists can examine a stone’s inclusions, measure its optical and physical properties, and view it under ultraviolet (UV) light as well as a Chelsea filter. In addition, if the stone has a documented history, knowing when different mines were active could narrow the possibilities even further.
Identifying emerald origins often requires expert knowledge and experience, and the best way to become familiar with the inclusions in emeralds from different sources is to spend time studying them. This guide is intended as an aid and reference in determining emerald origins based on properties observable with at-home gem lab equipment. However, for difficult separations, a gemological laboratory that can measure trace element composition will be more reliable.
Emeralds occur in Afghanistan’s picturesque Panjshir Valley as well as adjacent valleys. However, the geology surrounding deposits in these valleys differs, indicating three or more processes for emerald formation in the area. Because of this, gemological properties may differ between emeralds mined in relatively close proximity. Mining within the Panjshir Valley itself produces most Afghan emeralds, so gemological studies have focused on this deposit. Although emerald mining began prior to the 18th century, production of commercial quantities began in the 1970s and continues today.
Panjshir emeralds have overlapping refractive indices (RIs) with some emeralds from Brazil, Russia, and Zimbabwe, but their unique inclusions help distinguish them. For example, Panjshir emeralds often exhibit multi-phase inclusions with a liquid brine and multiple daughter crystals. These inclusions can also contain liquid and/or gaseous carbon dioxide. Two-phase inclusions of liquid and gaseous water are also common. In addition, tube-like inclusions along the c-axis, tabular crystals perpendicular to the c-axis, and subhedral crystals that form at their intersection also occur. Observed mineral inclusions are limonite, beryl, pyrite, carbonates, and feldspars.
Once an important source of emeralds for the Roman Empire, Habachtal, Austria is now depleted. These emeralds grew in a biotite schist and may contain biotite, muscovite, quartz, tremolite rods, chlorite, apatite, sphene, tourmaline, rutile, and epidote.
A reliable source of emeralds since the 1970s, Brazil has a number of emerald mining areas. The state of Minas Gerais is perhaps the most prolific, but mining operations in Bahia, Goiás, and Rio Grande do Norte are also commercially important. Although Brazil isn’t known for high-quality emeralds, recent production at some of these mines has yielded many carats of fine gems in addition to commercial-quality material.
Emeralds from the Bahia mining area grow in serpentinite rocks and are generally heavily included with two-phase inclusions, biotite, talc, dolomite, and liquid films. Large-scale emerald mining in this state began in the 1960s with the discovery of an economic-scale emerald deposit at Salininha. Deposits at Carnaiba and Socotó also produced emeralds on a commercial scale. The emerald-bearing rocks in this state are rich in molybdenum and frequently associated with molybdenite.
The state of Goiás hosts a number of emerald mines, one of the most prolific being the Santa Terezinha de Goiás deposit. This mine was most active from the 1970s through the 1990s. Emeralds from this deposit grew in a talc schist and are generally small, less than one centimeter in length. Cut stones are generally under one carat. Pyrite, chromite, talc, and calcite are the most common mineral inclusions. These emeralds also exhibit strong pleochroism, with dark greenish blue and pale yellowish green visible from different axes.
In Minas Gerais, the Itabira region hosts the largest emerald mine in Brazil: the Belmont mine. The emerald-bearing rock in this area is a biotite talc-chlorite schist, and emeralds are often associated with chrysoberyl and alexandrite. Two and three-phase inclusions may occur, along with flakes of mica, acicular growth tubes, and carbonate crystals. The deposit Sat Capoeirana is made up of the same lithographic unit as Belmont, so these emeralds have similar characteristics.
Emeralds from Minas Gerais exhibit similar RIs to Colombian and Afghan emeralds, and emeralds from all three sources may contain three-phase inclusions. A Chelsea filter test will help distinguish these emeralds. Stones from Minas Gerais show no reaction under a Chelsea filter, while those from Afghanistan and Colombia will.
Rio Grande do Norte
In 2006, miners found emeralds in the state of Rio Grande do Norte in a biotite schist associated with pegmatite veins. These rough emeralds are usually fragmented, with few hexagonal crystal shapes. In addition, these emeralds typically have small areas of transparency, generally from 2 to 5 mm, and often contain two-phase inclusions, parallel growth tubes, and fine, fiber-like inclusions. Mineral inclusions in these specimens include rounded plagioclase crystals, phlogopite platelets, hematite flakes, and quartz grains.
Two locations in China have reported emerald finds. One source is near the village of Davdar, close to the border with Pakistan. These emeralds contain fingerprint inclusions, fractures, and two and three-phase inclusions. They also contain numerous fine growth tubes parallel to the c-axis.
In 1992, gem-quality emeralds were uncovered in southern China’s Yunnan Province. These vanadium-dominant emeralds are low in iron and also contain numerous two-phase inclusions. In addition, tourmaline, arsenopyrite, mica, and feldspar mineral inclusions are present.
Colombia is the world’s most prestigious source of emeralds, as well as one of the most productive. Thus, determining whether an emerald originated in Colombia or elsewhere can have a big impact on pricing. Several commercial mines in Colombia produce emerald, but the two most prolific and famous are Chivor and Muzo. Chivor material tends to be blue-green, while Muzo emeralds are more yellowish green and deeply saturated. However, this distinction requires a trained eye and isn’t diagnostic. Other Colombian mines include Coscuez, Borbur, and Gachalá.
Three-phase inclusions were once considered diagnostic of Colombian origin. However, gem-grade emeralds from Afghanistan, Brazil, China, Mozambique, Nigeria, Norway, Tanzania, and Zambia may also feature these types of inclusions, so scrutinizing three-phase inclusions is essential for confirming emerald origins.
The three-phase inclusions in Colombian emeralds usually have irregular, jagged shapes. The gas bubbles in these inclusions are typically small and not larger than the crystal, which is usually cubic. Sometimes, the inclusions may contain multiple cubic crystals.
Three-phase inclusions in Zambian and Chinese emeralds typically contain multiple crystals, with one cubic and one more rounded, and sometimes even multiple daughter crystals. Meanwhile, inclusions in Afghan emeralds exhibit multiple transparent cubic and rounded crystals, and sometimes contain dark mineral inclusions. Mozambican emeralds can have multiple inclusions of isotropic daughter crystals of carbonate and nahcolite. Norwegian emeralds can contain multi-phase inclusions with dark crystal phases and elongated calcite crystals in addition to cubic halite. Inclusions in Tanzanian emeralds also contain multiple daughter crystals, including several different carbonates, quartzes, and chrysoberyls.
In addition, a Chelsea filter can readily separate Colombian from Brazilian origin. While Colombian emeralds will glow pink to red, Brazilian stones show no reaction.
Nigerian emeralds can also have similar features to Colombian emeralds. However, RI testing will reveal lower values for Nigerian emeralds than for Colombian.
Colombian Mine Origin
Determining the source mine can also be important for Colombian emeralds. Although some graders rely on differences in color, citing that Chivor emeralds typically show a more blueish green and Muzo emeralds have more yellowish hues, this isn’t diagnostic. Instead, a good RI reading can distinguish between the two sources once a Colombian origin is confirmed.
Certain gemological laboratories can determine the exact mine of origin through trace element analysis. Using a scanning electron microscope coupled to an energy-dispersive x-ray spectrometer, gemologists can measure trace amounts of vanadium, nickel, and magnesium. These serve as a chemical fingerprint for the source mine.
For any emerald with a potential Colombian origin, obtain an origin report from a reputable laboratory. Without this report, buyers may be unwilling to pay a premium for Colombian emeralds.
Although the mine isn’t currently active, the GIA has studied the gemological properties of Ancient Egyptian emeralds. These emeralds occurred in mica schists are are chromium-bearing but often show light color. As a result, a Chelsea filter test may be negative (yellowish green) to moderate (pink). Partially healed fractures of two-phase inclusions are numerous in these emeralds, and unhealed fractures are also present and may show limonite stains. Growth tubes parallel to the c-axis and inclusions of mica and amphibole are also present.
One of the most gemologically significant finds in recent decades is the discovery of Ethiopian emeralds. These gems, from a schist facies, look like Brazilian and Zambian emeralds. They feature blocky multi-phase inclusions and inclusions of biotite.
Emeralds have been found in the Indian states of Rajasthan, Tamil Nadu, Andhra Pradesh, and Orissa. However, only Rajasthan has had commercial mining, and its production in 1983. Emeralds produced were generally low-quality and highly included. Common inclusions are oblong cavities parallel to the c-axis with gas bubbles, biotite, fuchsite, apatite, two-phase inclusions, and comma-shaped groups of negative twin crystals (cavities).
An emerald deposit in northeastern Kazakhstan near Delbegetey produces gem-quality emeralds. These stones commonly exhibit blueish colors and color zoning. Elongated fluid inclusions parallel to the c-axis are common and often contain small mica inclusions at one end. Other fluid inclusions, healed fractures, and small mica inclusions are also present.
Two areas of Madagascar produce emerald: Mananjary and Ianapera. Emeralds in the Mananjary deposit form in a mica schist and have color and optical properties similar to Zambian emeralds. Quartz is one of the most common inclusions and is often associated with other inclusions. Other inclusions common in these stones include the following: micas, amphiboles, carbonates, feldspar, talc, chlorite, molybdenite, pyrite, barite, tourmaline, fluid inclusions, and two-phase inclusions. The fluid inclusions often appear in clusters or associated with quartz crystals. Many crystals exhibit color zoning, with the rim darker than the center of the stone.
Emeralds from the Ianapera region formed in a shear zone and are generally small and fractured. These emeralds tend to have a colorless core and deep green rim. The concentrations of chromophores vary widely in this deposit, with emeralds formed near pegmatites exhibiting very high concentrations of chromium and those formed further away having paler colors and less chromium. Some inclusions identified in these emeralds include the following: phlogopite, carbonates, barite, potassium feldspar, quartz, pyrite, zircon, monazite, bastnaesite, phenakite, and iron and chromium oxides. Two-phase inclusions with carbonate minerals are also observed.
A biotite-phlogopite-talc schist in eastern Mozambique near the village of Gité hosts an emerald deposit. These emeralds are typically blue-green in color and contain numerous cracks and inclusions. Fluid inclusions are abundant, and two and three-phase inclusions also occur. Three-phase inclusions may contain a carbon dioxide bubble, carbonate, and nahcolite (sodium bicarbonate). Quartz is also a common inclusion.
Central Nigeria hosts an emerald and green beryl deposit. The emeralds from this deposit exhibit strong growth zoning. In fact, scientists believe mineral growth started and stopped several times based on the growth bands and the presence of growth faces with numerous inclusions within each crystal. Crystal inclusions are rare, but fluorite and albite are the most common. Fluid inclusions are common, and two and three-phase inclusions also occur. These inclusions are often dark under transmitted light.
In the late 19th and early 20th centuries, a gem deposit at Eidvoll, Norway produced emeralds. Although much of the material was light in color, several gems of fine color also originated here. Fluid inclusions and multi-phase inclusions are common, with multi-phase inclusions mostly liquid with a large gas bubble and multiple solid phases. Solid phases can include a large cubic crystal of halite, an elongated calcite crystal, and one or more opaque crystals. These opaque solids are often sulfide phases such as pyrrhotite, galena, and sphalerite. In addition, crystal inclusions that resemble brassy pyrite cubes were observed in some samples.
Four areas of Pakistan produce emeralds: the Swat Valley, Malakand/Mohmand, the Bajaur Agency, and the Khaltaro area. Of these, the Swat Valley is the most economically important and widely studied. These emeralds form in shear zones in a talc-carbonate rock and have medium to deep colors. Certain inclusions in Swat Valley emeralds are similar to those found in synthetics. Filament-like inclusions and wavy liquid feathers can resemble inclusions in synthetic emeralds, so a novice may mistake these gems for synthetics based on their jardin. Fluid inclusions, thin films, and two-phase inclusions are common, and three-phase inclusions have been observed. Partially healed fractures associated with small two-phase inclusions are also common. Crystal inclusions are rarer in these emeralds, but calcite and dolomite have been observed.
A 1996 study assessed emeralds from Khaltaro. Rarely transparent and facet-grade, these specimens typically contain numerous fine cracks and inclusions of fluorite, albite, and biotite.
Although the gem-rich Ural mountains have yielded fine emeralds since the 1830s, miners encountered groundwater in the 1850s, prompting mining operations to stop. For nearly a century, emerald production was small-scale and sporadic. However, production resumed in the 1940s when the government mined the area for beryllium, producing emerald as a by-product. Mining slowed again in the 1990s but has picked up in recent years. Now, there are plans to expand the operating capacity tenfold by 2025.
Emerald-bearing rocks in this deposit include talc, mica, and actinolite schists. The emeralds produced here often exhibit growth structures parallel to the prism face, often confined to pale-color zones. Mica flakes and actinolite needles are common, and several types of liquid and two-phase inclusions are present. Of note are thin, flat cavities that appear as thin lines when the stone is viewed perpendicular to the c-axis.
The Leydsdorp mine in South Africa produces emeralds from the contact zone between biotite-talc and actinolite schists and intrusive pegmatites. These emeralds commonly range in color from a colorless or light green core to a darker, more highly saturated rim. Common inclusions in these emeralds are biotite, apatite, and quartz. Hematite, pyrite, pyrrhotite, zircon, molybdenite and galena may also form inclusions.
Locals discovered emeralds in the late 1960s near Tanzania’s Lake Manyara. Just a few years later, miners produced commercial quantities of gem-quality emerald and alexandrite. The surface of these rough emeralds are heavily etched, and these gems can contain a number of fluid and crystalline inclusions. Multi-phase inclusions can also occur, often with multiple crystalline phases of carbonate minerals, quartz, or chrysoberyl. Similar minerals may make up crystalline inclusions in these emeralds.
Emeralds occur in three different counties in North Carolina and have been mined since the late 19th century. Rough crystals generally have a light-colored to colorless core with an intensely colored rim, and rough stones show signs of etching. Although much of the material isn’t gem-quality, some high-quality stones have also come from this area. Quartz, calcite, pyrite, and rutile may occur as inclusions in these stones. In addition, emeralds from North Carolina fluoresce under longwave UV light, a property shared with few emeralds from other sources.
After Colombia, Zambia is perhaps the most significant of today’s emerald origins. This country hosts several mines, most located in the Kafubu area, although emerald mining began more recently at the Musakashi deposit. These two areas represent different emerald deposits with different geology, and their gems can be differentiated based on their inclusions. Common inclusions in Kafubu emeralds include phlogopite, actinolite, and apatite, while sphene, iron oxides, feldspars, quartz, zeolites, and three-phase inclusions are more common in Musakashi emeralds.
Kafubu emeralds tend to have a higher RI than Colombian emeralds, making them easy to distinguish. In addition, Kafubu emeralds may contain skeletal inclusions of magnetite or hematite, which haven’t been observed in other deposits. Trace element composition may also help to indicate origin.
Musakashi emeralds can contain three-phase inclusions, so distinguishing them from Colombian emeralds is important. Often, the three-phase inclusions in Musakashi emeralds contain at least two crystals, with one cubic and one more rounded. Several smaller crystals may occur as well. This is very rare among Colombian stones, but may occur in emeralds from Afghanistan.
The Sandawana mine in Zimbabwe produces a large quantity of small but high-quality emeralds. These gems have high chromium content and high RI and specific gravity (SG), making Zimbabwe easily distinguishable from most other emerald origins. Zimbabwean emeralds occur at the contact between pegmatites and greenschist and typically contain inclusions of actinolite and cummingtonite. Albite and apatite are also common. Fluid inclusions are typically small, and many fluid inclusions that had once existed are now empty.
|Minas Gerais (var.)||1.578-1.581||1.572-1.576||0.006-0.009||2.71-2.73|
|Goias (Sta. Terezinha)||1.588-1.593||1.580-1.586||0.007-0.008||2.70-2.76|
|Rio Grande do Norte||1.587-1.591||1.578-1.583||0.008-0.009||2.72-2.74|
|Madagascar||Mananjary: Ankadilalana Mine||1.588-1.591||1.581-1.585||0.007||2.68-2.73|
|South Africa||Transvaal, Gravolotte (Cobra Mine, etc.)||1.593-1.594||1.583-1.586||0.006-0.007||2.75-2.76|
Note: The previous table contains information from the Color Encyclopedia of Gemstones by Joel E. Arem, PhD, FGA. Some values have been amended to reflect current research. The table also contains new additional data for emeralds from Afghanistan, Rio Grande Do Norte, China, Ethiopia, Kazakhstan, and Nigeria.
|Country||Locale||UV-short reaction||UV-long reaction||Chelsea Filter||Pleochroism||Notes|
|Afghanistan||Panjshir||Inert||Inert||light red to reddish orange||pale yellowish green/pale blueish green|
|Brazil||Goias||Inert||Inert||Usually uneven color distribution, inert to pink||greenish dark blue/yellowish pale green|
|Minas Gerias||Inert||Inert||No reaction||very slightly yellowish green/blueish green|
|Rio Grande do Norte||Inert||Inert||Variable. Some show pink to red, others have no reaction.||Distinct to strong. light yellowish green/blueish green to greenish blue|
|China||Davdar||Inert||Inert||Weak red||Moderate. yellowish green/blueish green|
|Colombia||Chivor||Pink to strong pink|
|Coscuez||Inert||Inert or slightly pink, orange, or red||Pink to strong pink|
|La Pita||Pink to strong pink|
|Muzo||Pink to strong pink|
|Penas Blancas||Pink to strong pink|
|Egypt||Inert||Inert||Yellowish green to weak moderate pink||Weak to moderate. Yellowish green/blueish green|
|Kazakhstan||Inert||Weak red||Strong. Blueish green to green|
|Madagascar||Mananjary||Yellowish green/greenish blue to blue|
|Pakistan||Swat Valley||Inert||Inert||Very weak to weak red||Moderate. Very slightly yellowish green/blueish green|
|Russia||Urals||Weak. Yellowish green/blueish green|
|Zambia||Kafubu||Inert||Usually inert, sometimes faint green||No reaction or light pink to red||Strong. Yellowish green to greenish yellow/blueish green to greenish blue|
|Zimbabwe||Inert||Usually inert, sometimes faint green||Light pink to pinkish red||Yellowish green/blueish green|