EMERALD

Emerald is the bluish green to green variety of beryl, a mineral species that includes aquamarine.

OVERVIEW

Gem experts differ on the degree of green that makes one stone an emerald and another stone a less-expensive green beryl. Most gemologists, gemological laboratories, and colored stone dealers call a stone green beryl when its color is “too light” for it to be classified as emerald. Even among that group, however, there’s a difference of opinion about what’s considered “too light.”

Emerald is the green to greenish blue variety of beryl, a mineral species that also includes aquamarine as well as beryls in other colors.

Gem experts differ on the degree of green that makes one stone an emerald and another stone a less-expensive green beryl. Some people in the trade tend to give the name emerald to any green beryl colored by chromium. But to most gemologists, gemological laboratories, and colored stone dealers, it is more correct to call a stone green beryl when its color is “too light” for it to be classified as emerald. Even among that group, however, there’s a difference of opinion about what’s considered “too light.”

GIA uses lab-graded comparison stones to determine if the green color is dark enough and saturated enough to be called emerald.

WHERE IS IT FOUND ?

Colombia has been the source of the finest emeralds for more than 500 years, and Colombian emeralds are the standard by which all others are measured. Three mining sites in Colombia are particularly noteworthy: Muzo, Chivor and Coscuez. Each locality produces a range of colors but, generally speaking, darker tones of pure green emeralds come from Muzo. Emeralds that are lighter in tone and slightly bluish green are associated with Chivor. Slightly yellowish green emeralds are unearthed in Coscuez.

The May birthstone is also found in the state of Minas Gerais, Brazil. One of the most productive sites for the green birthstone is the sophisticated Belmont mine. Capoeirana is another important locality, a rugged region worked largely by independent miners and small-scale operations.

CARE & CLEANING

Emerald is a 7.5 to 8 on the Mohs scale of hardness, so it is more susceptible to scratching than a diamond, which ranks 10 on the scale. The May birthstone is often treated to improve its color or clarity. Common treatment methods include:

1. Dyeing: Paler emeralds with multiple fractures may be dyed green to enhance their color.
2. Fracture Filling: Oils, waxes, and artificial resins are often used to fill surface-reaching fractures in emeralds. The goal is to reduce the visibility of the fractures and improve the apparent clarity. The volume of filler material present can range from minor to significant; the different substances have varying degrees of stability.

The emerald birthstone requires some special care: Avoid exposure to heat, changes in air pressure (such as in an airline cabin) and harsh chemicals. Never put an emerald in an ultrasonic cleaner, as the vibrations and heat can cause the filler to sweat out of fractures. Filled emeralds can also be damaged by exposure to hot water used for washing dishes. The safest way to clean emeralds is to gently scrub them with a soft brush and warm, soapy water.

HISTORY

Emerald’s lush green has soothed souls and excited imaginations since antiquity. Its name comes from the ancient Greek word for green, “smaragdus.” Rome’s Pliny the Elder described emerald in his Natural History, published in the first century AD: “…nothing greens greener” was his verdict. He described the use of emerald by early lapidaries, who “have no better method of restoring their eyes than by looking at the emerald, its soft, green color comforting and removing their weariness and lassitude.” Even today, the color green is known to relieve stress and eye strain.

There are other green gems, like tourmaline and peridot, but emerald is the one that’s always associated with the lushest landscapes and the richest greens. Ireland is the Emerald Isle. Seattle, in the US state of Washington, is the Emerald City. Thailand’s most sacred religious icon is called the Emerald Buddha, even though it’s carved from green jadeite.

The first known emerald mines were in Egypt, dating from at least 330 BC into the 1700s. Cleopatra was known to have a passion for emerald, and used it in her royal adornments.

BIRTHSTONE

As the gem of spring, emerald is the perfect choice as the birthstone for the month of May. It’s also the gem of the twentieth and thirty-fifth wedding anniversaries.

FACT SHEET

Mineral: Beryl
Chemistry: Be3Al2Si6O18
Color: Vibrant green
Refractive Index: 1.577 to 1.583
Birefringence: 0.005 to 0.009
Specific Gravity: 2.72
Mohs Hardness: 7.5 to 8

Source of Content : www.gia.edu