Crystals are colored by Chromium and Vanadium.
Emerald is the most valuable gemstone, next to Ruby and considered one of the "precious four" of all the gemstones. GIA puts emerald in a "Type III clarity Gemstone, which means that even good quality emerald used in jewelry is included in the 12 to 13 range in clarity. Because of this designation, a clarity grade of “very slightly included” is the normal range for emeralds. Well over 90% of the emeralds in commerce have been treated to minimize the appearance of the inclusions. Emerald contains the ore beryllium.
Emerald is the Birthstone for the month of May.
Mineral Class: CycloSilicates
Mineral Species: Aluminum Beryllium Silicates
Composition: Beryl Group - This group includes Emerald, Aquamarine, Morganite, Golden Beryl and Bixbite.
Hardness: 7.5 to 8
Specific Gravity: 2.67 to 2.78
Cleavage: Indistinct, poor basal cleavage is seldom visible.
Fracture: conchoidal producing smooth brilliant surfaces, brittle
Color: Green, Yellowish Green, Bluish Green
Luster: Vitreous(glass-like) when cut & polished.
Transparency: most are heavily included,Translucent to opaque, very rarely transparent.
Crystal System: Hexagonal; 6/m2/m2/m
Crystal Habit: Typically small elongate first order prisms, often with vertical
striations and irregular pinacoidal terminations.
Sources: Columbia,Brazil, Aimbabwe, Afghanistan, Madagascar, Nigeria, Tanzania, and Zambia. Brazil and Zambia are among the leading producers of fine emeralds, following Colombia.
6.2G Rough Emerald
Untreated Rough Emerald
Color: Deep Green/Blue-green
Size: 6.49 grams
Description: Preformed Rough
Treatments: No oil or heat treatments
Origin: Ndola, Zambia, Africa
Emeralds from Zambia display an unusual blue tone, with blue-green/yellow green pleochroism, due to their high iron content (0.73%).