Gemology Fast Track / Unit 11 of 24 · Major species · 60 min
Beryl: emerald, aquamarine, morganite
Goal: Identify beryl varieties, read emerald inclusions and grade oiling.
7.5–8Hardness
1.565–1.602RI (varies)
0.004–0.009Bire · U−
2.67–2.90SG
Emerald
Cr and/or V. Type III clarity: inclusions expected ('jardin').
Aquamarine
Fe. Heated to remove green. Type I: clean.
Morganite
Mn. Cs-rich → higher RI/SG (up to 1.60, 2.90).
Heliodor / goshenite / red beryl
Fe-yellow / colourless / Mn³⁺ red (Utah, very rare).
Emerald inclusions = origin clues
Three-phase (jagged)Colombia: liquid + gas + halite cube.
Mica platelets, tremolite needlesSchist-type: Zambia, Brazil, Swat (Pakistan).
Pyrite, calciteColombia (black shale hosts).
Two-phase, comma shapesMany sources.
Gota de aceite'Oil drop' wavy growth texture in top Colombian stones.
TrapicheSix-spoke carbon pattern (Muzo).
Clarity enhancement (nearly every emerald)
NoneInsignificantMinorModerateSignificant
Fillers
Cedar oil (traditional), mineral oil, epoxy resins (Opticon etc.). Resins harder to remove, may whiten.
Detection
Flash effect (resins), flattened bubbles, dendritic dried residue, uneven lustre at fracture openings, UV glow of some oils.
Care
No ultrasonic, steam or solvents: they remove filler and reveal fractures.
Synthetic emerald separation
Flux syntheticRI 1.560–1.563, SG ~2.65 (floats where natural sinks in 2.65 liquid); wispy veils, Pt platelets; strong red under CF and UV.
Hydrothermal syntheticOverlaps natural RI/SG; chevron growth, nail-head spicules, seed plate. Lab confirmation.
Look-alikesTsavorite (SR 1.74), chrome diopside (1.67–1.70, bire 0.025), green tourmaline (bire 0.02), glass (SR, bubbles), soudé doublet.
Gems in this unit (19)
EmeraldTrapiche emeraldAquamarineMorganiteHeliodorGosheniteRed berylGreen berylMaxixe berylPezzottaiteChrysoberylAlexandriteCat's-eye chrysoberylAlexandrite cat's eyeBerylloniteSynthetic emerald (flux)Synthetic emerald (hydrothermal)Synthetic alexandriteSoudé emerald
Full gem records open in the members' Gem database.
Practical
Search GIA's gem encyclopedia images for 'three-phase inclusion emerald' and 'nail-head spicule synthetic emerald'. Draw both. Then compare aquamarine vs blue topaz properties side by side in the Database.
Unit quiz
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