Smaragd

Smaragd, also known as emerald in English, is the green variety of the mineral beryl (Be3Al2Si6O18). Its green color arises primarily from trace amounts of chromium and sometimes vanadium. The term smaragd is used in German and Dutch; the English name emerald derives from Latin smaragdus via Greek smaragdos.

Crystal structure and properties: Emerald crystallizes in the hexagonal system. Hardness on the Mohs scale is 7.5–8; refractive index about 1.576–1.589; birefringence 0.005–0.009; specific gravity 2.67–2.78. Emerald crystals are commonly prismatic with hexagonal cross-sections. Inclusions, often described as jardin or garden inclusions, are frequent and characteristic and can affect clarity.

Formation and sources: Emerald forms in pegmatites and hydrothermal veins associated with chromium-rich metamorphic rocks. Major sources include Colombia (Muzo, Coscuez, Chivor), Brazil, Zambia, Afghanistan, and Russia. Colombian stones are prized for vivid green color and low iron content; other sources yield stones with varying hue and clarity.

Treatments and synthetic varieties: Most commercial emeralds are oiled or resin-filled to improve clarity; some are fracture-filled or irradiated. Synthetic emeralds produced by hydrothermal or flux-growth methods are chemically and optically similar but typically offer cost advantages.

Value and care: Color saturation and clarity largely determine value, with cut quality also important. Clean emeralds with lukewarm water and mild soap; avoid ultrasonic cleaners on oiled or resin-filled stones. Store separately to prevent scratching, and obtain stones or settings with independent certification for authenticity and treatment details.