Emerald Characteristics: Properties and Facts Quiz

Study Notes

Mohs scale hardness: 7.5 to 8
Emerald is a variety of beryl
Most prized emeralds are highly transparent, with colors ranging from bluish green to green, and strong to vivid saturation
Iron content affects the color, with lower iron content producing a purer green color

Emerald is composed of beryllium, aluminum, silicon, oxygen, and one or more of the trace elements chromium, vanadium, and iron

Emeralds are formed in metamorphic-rock environments, where pegmatites intersect with schists (e.g. Brazil)
They can also occur in sedimentary rock environments, associated with hydrothermal veins (e.g. Colombia)

Dichroism: a phenomenon that occurs when the cutter orients the table perpendicular to the crystal's length, resulting in a prized bluish green color
Clarity characteristics: color zoning, fractures, liquid and multiphase inclusions, mineral crystals, needles, and growth tubes
Trapiche emerald: a type of emerald with dark inclusions that extend from the center of the crystal, forming a pattern that looks like the spokes of a wheel
"Oil-drop effect": a phenomenon that occurs in the finest Colombian emeralds, producing a roiled pattern similar to honey or oil

Common treatments: oiling or fracture filling, dyeing
Common cuts: emerald cut, round, oval, pear, marquise, or heart shapes, in brilliant, step, or mixed-cut facet arrangements
Calibrated sizes: 5x3 mm through 7x5 mm range, with calibrated rounds available in sizes below 4 mm

"Colombian" is commonly used to describe the finest emerald color
"Zambian" is often used to describe emeralds that are slightly darker and more bluish than Colombian emeralds
"Jardin" is used to describe inclusions
Countries of origin: Colombia, Zambia, Brazil, Afghanistan, Pakistan, Russia, Zimbabwe, Madagascar, and China

Flux and hydrothermal are the main synthetic processes used to produce emeralds, with hydrothermal being the primary method
Jacques Joseph Ebelman was the first to use the flux process to synthesize emerald crystals, and Johann Lechleitner synthesized emerald hydrothermally in 1960