Emerald
| Refractive Index : 1.583 – 1.577 (+0.017 – 0.017) |
| Optical Characteristic : DR U- |
| Specific Gravity : 2.72 (+0.18 – 0.05) |
| Formula : Be3AI2Si6O18 |
| Crystal System : Hexagonal |
| Variety/Species : Emerald |
| Species/Group : Beryl |
| Birefringence : 0.005 to .009 |
| Dispersion : 0.014 |
| Hardness : 7.5 to 8 |
| Toughness : Poor to good |
| Ultrasonic : Never |
| Steam : Never |
| UV Long : Inert to strong |
| UV Short : Inert to strong |
| Pleochroism : 2 Colors |
| Strength : Moderate to strong |
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| Pleochroism Colors : Moderate to strong blue-green/yellowish green or (rarely) blue/yellowish green. |
| Heat : May fracture |
| Acids : Avoid hydrofluoric acid |
| Light : Stable |
| Polish Luster : Vitreous |
| Fracture : Conchoidal |
| Fracture Luster : Vitreous to resinous |
| Clarity Type : III |
| Tones : 3-8 |
| Saturations : 2-5 |
| Cause of Color : Usually chromium,sometimes vanadium,or both |
| Enhancements : Oiling,Opticon |
| Cleavage : Indistinct. |
| Color Range : Strongly, bluish green, green |
| Transparency : Transparent to Translucent (highly included stones) |
| Phenomena : Chatoyancy, Asterism. Asterism is rare. |
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| Separations : Natural Emerald from- Flux syn.emerald (except Gllson type III) : Magnification, RI, birefringence, fluorescence, SG Gilson Type III : Magnification, spectrum (possibly) All triplets : Magnificaation, immersion, RI(poosibly) Hydrothermal synthetic emerald : Magnification, fluorescence Hydrothermal overgrowth/sandwich : Magnification, fluorescence,immersion Dioptase : RI, birefringence, SG, cleavage, magnification |
| Identifying Characteristics and information Pyrite, calcite and mica inclusions, tremolite needles, 9-phase inclusions. |
| Spectral Data Distinct lines at 6830 and 6805. Less distinct at 6620,6460. Partial absorption between 6300 and 5800 |
| Trade Names and Misnomers Brazilian Emerald Colombian Emerald Emerald Russian Emerald Sandawana Emerald Siberian Emerald Zambian Emerald |
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