The Emerald
Emerald is a gemstone of unique beauty and intense green color. Formed in the depths of the Earth for millions of years, this precious beryl stone enriched with chromium and vanadium has always embodied elegance and refinement.
Emerald is one of the green varieties of beryl, prized for its brilliance and intense hue. Other members of the beryl family, each with a different color, include aquamarine (blue), morganite (pink to orange), heliodor (golden, yellow-green, green-yellow), black beryl (dark gray to black), yellow beryl (light yellow), green beryl (light green), goshenite (colorless), red beryl (purplish-pink to red), and pezzottaite (light pink to bright pink). The intense green color of emerald is due to the presence of inclusions of chromium, and sometimes vanadium, while green beryl gets its color from inclusions of ferrous and ferric iron.
The most famous emerald deposits are found in Colombia (Muzo, Chivor, Coscuez), Zambia (Kitwe), Brazil, Afghanistan, Pakistan, Russia, and Madagascar. Colombia, however, remains the country most renowned for the exceptional quality of its emeralds.
In its natural state, emeralds are often marked by small inclusions, called “gardens,” which appear as cracks or frost. To reduce these inclusions and improve transparency, a colorless oil impregnation treatment is often applied. This process is commonly accepted when selling. However, impregnations with resin or colored glass, which further alter the natural appearance of the emerald, are more controversial and must be explicitly mentioned by the seller.
Emerald is a precious gemstone, coveted throughout the world and used in luxurious jewelry creations. High-quality emeralds, with a deep green and remarkable transparency, can reach prices exceeding 10,000 euros per carat (1/5 of a gram) for natural stones weighing more than 5 carats and containing few inclusions.
Some emeralds, particularly from Colombia, have rare effects such as asterism (cat’s eye effect) or trapiche formation, a fascinating star pattern highly prized by collectors.
Synthetic emeralds, produced in the laboratory by anhydrous or hydrothermal dissolution methods, have the same physical and optical characteristics as natural emeralds. Only an experienced gemologist or a gemological laboratory can distinguish them. For any acquisition, it is recommended to turn to a reliable expert to guarantee the authenticity of your emerald.
Physical properties of emerald:
Each gemstone has unique characteristics, such as color, clarity, and hardness, that influence its brilliance and durability. These properties are the result of the stone's chemical composition and crystal structure, which contribute to its appeal in jewelry and fine jewelry.Here are detailed resources on this topic.
Chemical composition: Beryllium-aluminium (Be₃Al₂(SiO₃)₆) with traces of chromium and sometimes vanadium (responsible for the green colour).
Hardness: 7.5 to 8 on the Mohs scale (softer than diamond, but still strong).
Density: About 2.7 to 2.8 g/cm³.
Crystal system: Hexagonal (trigonal).
Cleavage: Imperfect, along the basal plane.
Fracture: Conchoidal to irregular, with rougher and rounded edges.
Specific gravity: Varies from 2.67 to 2.78.
Melting temperature: About 1250 °C.
Optical properties of emerald:
Transparency: Transparent to translucent (inclusions may affect transparency).
Refractive Index: Between 1.565 and 1.602.
Birefringence: 0.005 to 0.009, creating a slight double refraction effect.
Brilliance: Vitreous, with a beautiful luminosity.
Color: Intense green, due to impurities of chromium and sometimes vanadium; the hue can vary from bluish green to yellow-green.
Fluorescence: Low to nonexistent, although some emeralds can emit a slight red fluorescence under UV.
Saturation: Generally intense color, with saturation and hue greatly influencing its value.
Pleochroism: Slightly present, emerald shows subtle variations in hue ranging from green to blue-green depending on the viewing angle.
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