Emerald
The mineral beryl carries the chemical formula Be3Al2(SiO3)6. Emerald is simply a green variety of this same mineral. A trace amount of chromium or sometimes vanadium provides the distinctive color. This cyclosilicate structure occurs alongside quartz, muscovite, and albite in nature. The Mohs hardness scale rates emerald between 7.5 and 8. Most stones contain many internal flaws known as inclusions. These imperfections result in generally poor toughness against breakage.
Color remains the most important criterion for grading any colored gemstone. A fine emerald must possess a pure verdant green hue with high transparency. Yellow and blue serve as normal secondary hues found within the crystal. Only gems that are medium to dark in tone qualify as true emeralds. Light-toned gems carry the species name green beryl instead. Eye-clean stones command the highest prices if they lack visible inclusions. Stones without surface-breaking fissures remain extremely rare. Faceted shapes like the oval cut or signature rectangular emerald cut appear most commonly.
Most emeralds undergo oiling during the post-lapidary process. Cedar oil fills surface-reaching cracks to improve clarity and stability. Other liquids including synthetic oils and polymers like Opticon also fill fractures. The least expensive emeralds often receive epoxy resin treatments. These methods open pores under mild heat in vacuum chambers. The U.S. Federal Trade Commission requires disclosure of this treatment upon sale. Untreated emeralds must carry a certificate from an independent laboratory. Gems grade on a four-step scale ranging from none to highly enhanced.
Ancient Egypt mined emeralds at Mount Smaragdus since 1500 BC. Roman and Byzantine Empires exploited these sites on an industrial scale. Mining ceased there after Colombian deposits were discovered. Colombia remains historically the world's largest producer today. Production increased by 78% between 2000 and 2010 alone. Three main areas drive output: Muzo, Coscuez, and Chivor. Zambia ranks as the second biggest producer globally. The Kagem Mines near Kitwe supplied 20% of global gem-quality stones in 2004. In early 2011, those mines produced 3.74 tons of material.
Researchers use energy-dispersive X-ray spectroscopy to trace chemical differences. American gemologist David Cronin examined fluid dynamics and precipitation mechanisms. His work demonstrated chemical homogeneity within specific mining locations. Statistical differences exist between emeralds from different mines. These distinctions separate stones from Muzo, Coscuez, and Chivor in Colombia. Traditional research relied on color, cutting style, and fracture filling types. Modern studies uncover subtle elemental variations even between nearby deposits.
Carroll Chatham developed the first commercially successful synthesis process around 1964. Pierre Gilson Sr. began producing flux emeralds that same year. Gilson's crystals grew at a rate of 1 mm per month. Hydrothermal synthetic emeralds appeared later with Johann Lechleitner of Innsbruck. Linde Division of Union Carbide created fully synthetic versions from 1965 to 1970. Tairus currently leads production of hydrothermal emeralds today. These stones mimic the composition found in Colombian alkaline deposits. Many synthetics remain inert to ultraviolet light during testing.
Emerald serves as the traditional birthstone for May. Alchemical lore claims the stone counteracts poison and cures leprosy. Hernán Cortés looted an emerald from Mexico bearing engraved text. French writer Brantôme recorded this artifact in the early 1600s. The idol at India's Meenakshi Amman Temple is thought made of emerald. L. Frank Baum featured an Emerald City in his 1900 novel. The Mogul Mughal Emerald dates back to 1695, 1696 AD. Today, notable specimens like the Bahia Emerald weigh over 341 kg.
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Common questions
What is the chemical formula for emerald?
The mineral beryl carries the chemical formula Be3Al2(SiO3)6. Emerald is simply a green variety of this same mineral.
How hard is an emerald on the Mohs scale?
The Mohs hardness scale rates emerald between 7.5 and 8. Most stones contain many internal flaws known as inclusions that result in generally poor toughness against breakage.
Where are the largest emerald deposits located today?
Colombia remains historically the world's largest producer today with three main areas driving output: Muzo, Coscuez, and Chivor. Zambia ranks as the second biggest producer globally.
When did mining begin at Mount Smaragdus in ancient Egypt?
Ancient Egypt mined emeralds at Mount Smaragdus since 1500 BC. Roman and Byzantine Empires exploited these sites on an industrial scale before mining ceased there after Colombian deposits were discovered.
Who developed the first commercially successful synthetic emerald process?
Carroll Chatham developed the first commercially successful synthesis process around 1964. Pierre Gilson Sr. began producing flux emeralds that same year while Linde Division of Union Carbide created fully synthetic versions from 1965 to 1970.