Emerald is a gemstone and a variety of the mineral beryl. composed of beryllium aluminium silicate with the chemical formula Be3Al2Si6O18.
One of the five cardinal gems,
Well-known varieties of beryl include emerald and aquamarine.
The word “emerald” comes from smaragdos, ancient Greek for a green gem. Roman author Pliny the Elder, who died in the 79 CE eruption of Mt. Vesuvius, wrote in his encyclopedic Natural History that “nothing greens greener”.
Beloved for millennia, it evokes rebirth and renewal. The birthstone of May. Widely regarded as the definition of green. From the poetic description of Ireland as “the Emerald Isle” to the vibrant green of the famed gemstone itself.
Legend has it that emerald has the power to make its wearer more intelligent and quick-witted, and it was once believed to cure diseases like cholera and malaria. The gemstone is now given for the 20th and 35th wedding anniversaries.
Colourless when pure, it is frequently tinted by impurities; possible colours are green, blue, yellow, pink, and red (the rarest).
The green colour comes from trace amounts of chromium or sometimes vanadium.
Beryl has a hardness of 7.5–8 on the Mohs scale. Emerald isn’t well suited to everyday wear, such as engagement rings due to it being soft and brittle.
The intensity of the green in the finest emeralds might not be equalled by anything else in nature.
The most desirable emerald colours are bluish-green to pure green, with vivid colour saturation and a tone that’s not too dark.
The most prized emeralds are highly transparent. The colour evenly distributed, with no eye-visible colour zoning. If the hue is too yellowish or too bluish, the stone is not emerald but a different variety of beryl, and its value drops accordingly.
Emerald appearance is sometimes associated with its mine location. Colombian emeralds are said to have a warmer and more intense pure green colour. Zambian emeralds are said to have a cooler, more bluish-green colour. Despite these theories, the truth is that emerald appearance overlaps between sources.
Emeralds typically contain inclusions that are visible to the unaided eye. Inclusions are excepted in emeralds.
Emeralds are graded by eye, unlike diamonds, where the 10× magnification is used to grade clarity. Thus, if an emerald has no visible inclusions to the eye, it is considered flawless. Because they’re so rare, eye-clean emeralds are incredibly precious.
To improve the appearance of an emerald, inclusions are sometimes filled with oils, waxes, and “artificial resins” —to reduce the visibility of the inclusions and improve the apparent clarity. These substances have varying degrees of stability, and the volume of filler material present can range from insignificant to major amounts. Filled emeralds can be damaged by exposure to hot water and detergents used for washing. Emerald is a gemstone and a variety of the mineral beryl.”
