Emerald
Smeraldo
Be₃Al₂Si₆O₁₈ Properties
- Color
- Green, green-blue
- Luster
- Vitreous
- Density
- 2.76 g/cm³
- Category
- Gem
Emerald is a variety of beryl colored by chromium and sometimes vanadium, considered one of the four classical precious stones alongside diamond, ruby, and sapphire. Its intense green is among the most sought-after colors in world gemology.
The characteristic green color derives from the presence of chromium (Cr³⁺) and, to a lesser extent, vanadium within the beryl crystal lattice. Inclusions in emerald crystals — called jardin (garden) in gemological terminology — are so common that they are accepted as evidence of natural origin.
The majority of commercial emeralds are treated with cedarwood oil or resins to improve their transparency. An emerald completely free of inclusions is rarer than an equivalent diamond.
Belongs to the beryl group, a cyclic silicate with a ring structure. The refractive index ranges between 1.565 and 1.602, with birefringence of 0.005–0.009. Determination of geographic origin is based on characteristic inclusions and LA-ICP-MS analysis to quantify Cr, V, Fe, Cs, and Li.
Mining localities
- Muzo e Chivor, Colombia (qualità più elevata)
- Kafubu, Zambia
- Itabira, Minas Gerais, Brasile
- Zimbabwe
- Pakistan
