May Birthstone – Emerald

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Emerald fact file
Crystal Structure: hexagonal
Chemical Composition: Beryl – silicate of Beryllium and Aluminum Al2Be3(Si6O18)
Hardness: 7.5 to 8 MOHS
Refractive Index: 1.57 to 1.60
Colors: light to dark green

Emerald, the green beauty of the gem world, is the May birthstone.

This beryl with traces of chromium, is said to increase both intelligence and strength of heart. Cleopatra was a great fan of emerald and so were the moghuls of India.Fine emeralds are probably among the rarest of gems. They are probably rarer than fine diamonds

Physical and Chemical Properties

Chemical composition

Emerald is a green to blue green variety of the mineral Beryl, which has a slightly complex chemical formula: Al2Be3(Si6O18)a silicate of Beryllium and Aluminum., 7.5 to 8 hard, 2.65 to 2.75 in specific gravity. Emeralds, as all other beryls, can range from being opaque to transparent. Beryl has fairly low optical properties. The refractive index ranges from 1.57 to 1.60 with many gems falling in the 1.572 – 1.580 range. Beryl has a low birefringence and are only weakly doubly refractive. It would take a piece of beryl about 15 inches thick to show a double image. The dispersion of beryl is also quite low (0.014) and emerald, as other beryl gems, has to essentially make it on color and pleasing appearance without the brilliant flashes of light that we associate with diamonds or gems with a very high refractive index or dispersion. Emeralds are usually clouded by many inclusions.


Emerald owes its color to a small percentage of Chromium Oxide in the crystal lattice—up to 3%. Strangely, this is the same oxide in the same percentage that imparts the red color to ruby when it is in the corundum lattice. Emeralds vary in color from light to dark green and most have inclusions, which are made of substances that become trapped in the formation of the gem. Completely transparent emeralds can be so rare that they are valued higher than diamonds.

Healing Properties and Interesting Information


The stone of successful love, Emerald is said to provide for domestic bliss and to instill both sensitivity and loyalty within the self and within others. It can be used to open, activate and stimulate the heart chakra, while helping to quiet the emotions. This May birthstone brings harmony to ones life.

Where Found

Emeralds are quite rare because of the rather limited geologic environment in which they can occur. Most emeralds form in contact metamorphic rocks—that is, the narrow, baked zone where a hot magma (lava) comes into contact with sedimentary rocks such as limestone or shale. Many emeralds come from contact metamorphosed black shale beds. Some emeralds form in limestone that has been subjected to contact metamorphism. In the United States, few emeralds have been found and most have been recovered from near Hidden, North Carolina. Almost all emerald is mined from in situ localities or deposits that are very close to the mother lode. This is because the emerald is a very weak stone—it will not endure the abuse and rigor of transportation in streams or in glacial ice. Australia has been a fairly important producer of emeralds. Several important sites in New South Wales and Western Australia have been described. The earliest known source for emeralds was called Cleopatra’s Mine, located near the Red Sea in ancient Egypt. Other sources of emeralds include Columbia, Brazil, Austria, India, Australia, Egypt, South Africa, and the United States (North Carolina).

History, mythology

In ancient Rome people associated emeralds with the goddess Venus because the stone symbolized reproduction. Also believed to give a person psychic powers, Emerald could tell if a lover’s affections were true. During the Middle Ages, people believed emeralds could stop bleeding and fevers and calm a person’s mind. The stone was also connected to eyesight, and one legend reports the gem could blind snakes while they were being charmed. Today, emeralds are associated with the themes of rebirth, romance, and spring.

Buying and Caring tips

Tips for Buying Emerald Jewelry

There is no firm boundary between emeralds with a heavy blue tint or aquamarine with a heavy green tint and there is no firm boundary between the green to blue green of emerald and the green of green beryl. The low physical and optical properties of emerald make it easy to separate from other gems such as peridot (very strong double refraction); tourmaline (strong double refractions and thready inclusions); tsavolite garnet (singly refractive); and glass (bubbles, swirl marks, etc.). Separating synthetic from natural emeralds is a bit more difficult. The synthetic will usually contain tiny crystals of the flux that was used in the solution, or it may contain micro-phenakite crystals or micro-platinum crystals. Inclusions that are wispy or cob-web like also are seen in many synthetic emeralds. For a one-carat stone of average-to-good quality you can expect to pay between $250 and $10,000 per carat. Of course, truly fine gems will cost more.

Tips to take care of Emerald Jewelry

Clean with a soft, damp cloth, warm water and a soft brush. Do not use mechanical cleaners. Avoid chemicals and heat that dissolve oils used during cutting and processing to conceal inclusions. Although emerald is harder than quartz, its crystal structure makes it brittle. Have a jeweler re-oil your emerald every few years. Avoid impacts.

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