|
|
www.mineralgallery.co.za Minerals A-E |
|
|
Emerald |
||
Name
Emerald
Chemistry
Be3Al2(SiO3)6
Uses
As gemstones
Color
Green or blue-green
Hardness
7.5-8
Specific gravity
2.6-2.9
Emerald is the most valuable of gems. It is the transparent green variety of the beryllium alumino silicate mineral beryl that owes it's green color to small amounts of chromic oxide. It is a relatively hard stone, 7.5 on the Moh's scale. The emerald (Greek: Smaragdos) of the ancients probably referred to a number of green stones. Lacking the fire and brilliance of the diamond, emerald is usually step cut, with elongated narrow facets and an oblong table, to enhance its color.
Emerald has been obtained from the schists of Cleopatra's mines, rediscover in 1818 in the Sikiat-Zubara region of Egypt. Vast quantities were taken from South America during the Spanish conquest, but the original mines have since been lost. The finest stones come from Columbia where they are mined from the calcite veining bitumous limestone at Muzo, Cosauez, and Somodocco and Bogoti.
The Emeralds that we have in our facet stone section comes from Zimbabwe and they are known as the Sondawana emeralds. They have stunning color and is known for the inclusions inside. Some emerald have also been found in Zambia. A lot of superstition surrounds the emerald.
Zambian emerald although discovered in the late 40's was not commercially mined until the 1950's. Today Zambia is one of the worlds's leading producers of fine Emerald. Highly prized for its intense color and remarkable clarity, Zambian Emerald retains its magnificent hue even in small stones of less than 0.5 ct. Although the experienced professional could identify a Zambian emerald in a Bond Street window, the chances are that it will be sold as a 'Sandawana' stone since the exporting of Zambian rough has long been considered a clandestine event and therefor does not lend itself well the respectability projected by the top jewelers shops of the world.
Much legend, lore and illusion are used by the trade when it comes to selling a fine emerald. Antiquity now seems to be the order of the day. Some dealers refer to emeralds as "Old Mine" and offer wonderfully supportive tales as to how the stone found its way through the centuries. Although much research has been done to establish the source of the 'Old Mine' (believed to have been in India) it still remains a mystery. This does not appear to deter the buyer and 'Old Mine' stones have been known to change hands for as much as US$ 30,000 per carat.
Colombia, much sought after for the large crystals and therefore bigger stones. However the material does not suit small stones and invariably is more included than its Zambian brother.
Zimbabwe: Sandwana mine is well known for its similarity to Zambian material. Steady production from this mine has been bolstered by Zambia’s illegal exports, rendering an even greater reputation as a reliable source.
Brazil, Madagascar, Mozambique, Russia and Nigeria also produces an 'Emerald' colored by vanadium but it is not intentionally recognized as emerald since the chromium content is too low.
It is the birthstone of May. It is treated with colorless oil or wax, or natural and synthetic resins into voids to improve appearance. Surface cavities of emeralds is commonly filled with a hardened colorless substance.
Superstitions abound concerning the emerald, birthstone for May: it supposedly soothes the eyes, preserves chastity, cures dysentery, prevents epilepsy, drives away evil spirits, and facilitates childbirth symbolizes youth and rebirth and believed by the ancients to empower the owner with foresight into the future.
As one of the most revered of all gemstones, Emeralds are a variety of the mineral Beryl and are mined in Columbia, Brazil, and Zambia. They are cut in a number of different shapes including round, marquise, oval, pear shapes, squares, cabochon, as well as the traditional emerald cut or step-cut shape.
Emeralds are graded principally according to color, clarity and shape. For simplicity, the grades are usually called Commercial, Good, Fine, and Extra Fine. Each grade represents a range of qualities.
Emerald Enhancements
Most emeralds have inclusions which can be regarded as its natural birthmarks that distinguish them as truly natural gemstones. Early gem merchants from India sought to enhance the color of emeralds by immersing them in clear oils and paraffin. They discovered that clear oils and waxes rendered surface fractures nearly invisible to the naked eye.
Today, most emeralds are oiled. Oiling is the oldest and most widely used treatment and is done in most places in the world. It is a process used to enhance the clarity of emeralds and is relatively easy to identify by a gemologists. In practice, clear oil is applied to the emerald and seeps into the emerald through surface fractures. Oiling is generally not permanent and may need to be reaplied every few years. While colorless oil is considered an acceptable practice, the use of green oil is considered a deceptive practice.
Today, there are many sophisticated techniques with which to improve the clarity of emeralds. In addition, to oils and waxes, there are now clear resins called Opticon that is sometimes applied to an emerald that seals surface fractures. In contrast to oiling, Opticon is loner lasting. Opticon is considered an acceptable practice, except when green dye is used to enhance the emerald's color.
Emerald Value
Emeralds are one of the most rare and valuable of all gemstones. While commercial grade emeralds are quite plentiful, fine and extra fine quality emeralds are very, very, rare. For purposes of illustration the following table indicates the range of retail prices that could be typical for a 1 carat emerald ( prices are for comparison only, exact prices vary according to market demand).
Quality Grade Low to High Retail Price Range for 1.0 Carat Emerald
Commercial $30.00 to $525.00
Good $525.00 to $1,125.00
Fine $1,125.00 to $2,900.00
Extra Fine $2,900.00 to 9,800.00
Similar to other gemstones, larger emeralds are much more rare than smaller sizes. Accordingly, larger emeralds command much higher prices. For instance, while a one carat (1.0 ct.) good quality emerald may sell for somewhere between $525 and $1,125, a five carat (5.0 ct.) emerald of similar quality could sell for between $7,500 and $15,000 ( prices are for comparison only, exact prices vary according to market demand).
Quality Grade Low to High Retail Price Range for 5.0 Carat Emerald
Commercial $300 to $7,500
Good $7,500 to $15,000
Fine $15,000 to $32,500
Extra Fine $32,500 to $95,500
The effect of oiling or the use of Opticon on the price of an emerald depends on its quality. For most qualities of emerald sold in jewelry, the effect on the price is negligible. However, for fine to extra fine emeralds, a non-oiled gemstone could command from 30% to 60% higher
The rich green emerald holds within it the promise of new life in springtime. How appropriate that it should also be considered the May birthstone.
Long ago the emerald was dedicated to Venus, the goddess of love. Lovers were told that this gemstone could reveal the faithfulness of their beloved. Faithfulness was reflected in a fresh, bright green color; a cheating heart was betrayed by a lifeless color.
Emeralds have always been highly prized by royalty. Cleopatra, queen of Egypt wore emeralds from her mine in Upper Egypt. Emeralds are heavily represented in the Russian Crown Jewels from the time of the czars. The Emperor Nero is said to have gazed through a large emerald to soothe his eyes as he watched the gladiator games in the Coliseum.
The ancients prized the emerald highly and believed it held many powers. They felt it could endow the wearer with the ability to think clearly in the past, present and future. It was supposed to improve one's memory, promote eloquent speech, quicken intelligence and endow the ability to foretell the future. It was also believed to promote honesty and frugality. Powdered and taken as a medicine, it was considered a preventative of epilepsy and other serious disorders.
Like many other gems, emerald had to share its earliest fame with other green gems which had not yet been recognized for their uniqueness. Also called emerald by the ancient Romans were green sapphire, turquoise, smithsonite, malachite, jasper and glass. According to the historian Pliny, the Romans believed that emeralds ripened into their color, so gems with light patches or consistent paleness were considered immature.
The emerald's exciting color has always been its lure. Even uncut, unpolished crystals are immediately recognized as something special. Indeed, when evaluating emeralds, color is the most important quality factor. Included crystals and cavities are not a hindrance unless they weaken the stone or cause it to appear cloudy or muddy. In fact, emerald inclusions often create a graceful, branch-like pattern known as a "jardin" (French for "garden").
A colorful history
Colombia, South America has always been the source of the finest emeralds. When the Spaniards conquered the Incas in the early 16th century, they stole all the emeralds they could find. However, the Incas refused to reveal the source of these coveted gems, and fortunately, the jungle quickly grew over the paths to the mines. The precious treasure was safe from the plunderers---at least temporarily. In 1555 one of the mines of Muzo was discovered by accident, and the Spanish began mining.
Colombian emeralds are a relatively clear pure green, slightly yellowish-green or slightly bluish-green. The only neighboring country to Columbia that is important as an emerald source is Brazil. Other sources are the African countries of Tanzania, Zambia and Zimbabwe.
The two most famous emeralds are the Devonshire and the Patricia. The Devonshire is a 1383.95-carat, uncut Colombian crystal of fine green color. It was given to the sixth Duke of Devonshire by Emperor Dom Pedro I of Brazil in 1831. It is on permanent loan to the British Museum of Natural History. The 630-carat Patricia Emerald is another crystal of fine color that resides in the American Museum of Natural History in New York City.
Duplicating nature
Synthetic emeralds first became commercially available in the 1940's. This was a tremendous technological improvement over the imitations which had been substituting for emeralds for generations. The synthetic is physically, optically and chemically identical to the natural gemstone. It is the result of the scientist's attempt to duplicate nature's processes in the laboratory.
Jewelry fashioning
The most popular cut for emeralds is a rectangular step cut. As a matter of fact, this cut is so widely used, the cut itself is often called the emerald cut. It is preferred because it shows fine color to the best advantage.
Emeralds are used in a wide range of jewelry styles from dainty pinkie rings to the most extravagant emerald and diamond necklaces. Quality and prices vary just as much. Emeralds are popular as center stones in rings, earrings and pendants, either encircled or offset by diamonds. Small emeralds are often combined with diamonds in cluster rings or pins or set into an anniversary ring. They are sometimes carved into exciting ring stones or pendants.
