Emeralds are found in granites, pegmatites, and schists, as well as alluvial deposits. Some emeralds find their way into gravels where the action of the water tumbles and smoothes them to they resemble shiny pebbles. The first known emerald mines were in Southern Egypt and show evidence of being worked in since 2000 BC. Some of the finest stones today come from Columbia, the best ones from the Chivor and Muzo mines. Much smaller quantities of medium-light color emeralds come from Brazil. Emeralds also come from Austria, India, Australia, Brazil, South Africa, Egypt, the USA, Norway, and Pakistan. In the last few decades, increasing quantities of emeralds have also been found in Zimbabwe, Zambia and Tanzania. These stones tend to be a very strong color, as are the stones from India, Pakistan and the Soviet Union.
Only the finest quality emeralds are clear and flawless. Most have tiny mineral inclusions or fractures, referred to as “jardin,” from the French word meaning garden. This refers to the moss or branch like appearance of the flaws. Flawless emeralds are rare and extremely valuable and usually only found in small sizes. There are fewer fine large emeralds in the world than there are diamonds! Most large emeralds have cracks and flaws, or are cloudy in color. It is common to oil these emeralds to disguise the flaws and enhance the color. The inclusions are sometimes not visible to the naked eye, especially in high quality stones. In these, they are very faint and only show up in a 10x, 20x, or 40x lens.
Emeralds are brittle and easily fractured during handling and setting. They are classified with a hardness of 9. They are not as hard as diamonds, but do last a long time. They scratch easily but the scratches can be wiped off. Emeralds range in color from light to dark green. The shade of green is determined by the presence of chromium oxide and vanadium. Throughout history, the emerald’s green color is said to have “entranced humankind.” Its color is a symbol of new life and the promise of spring, which is why it is the birthstone of May. Some call the green color of an emerald rich grass green, or limpid, velvety grass green, or deep transparent grass green with a luster. A square cut to the emerald actually emphasizes the richness of color by leading the eye into it rather than deflecting attention away from it. Some people actually prefer the off shades of green that are not perfect.
In ancient times, many gemstones were called emeralds just because they were green. Today there are about six or seven types of stones that are called various different kinds of emeralds. A true emerald however, is called simply an emerald, with no qualifying name in front of it.
Do not leave your emerald ring on while washing dishes or using soap as an emerald will attract grease and soap. After a while, these substances will accumulate on the bottom of the gemstone, causing it to lose its lively brilliance. Also do not wear your emerald when you might be engaging in physical activity that might scratch the stone. To clean your emerald, use room temperature running water and a soft toothbrush with mild soap like hand soap or Woolite. Brush repeatedly on the underside of the emerald to remove accumulations of dirt and grease. You will see the emerald begin to brighten. It should then be rinsed with warm water, and patted dry.
Do not clean an emerald in ultrasonic cleaners, steam cleaners or acetone. These may cause damage to the stone or the setting. An emerald should never be exposed to high heat. A good rule of thumb is that if the cleaning solution you use is too hot for you to put your hand in, you should not place your emerald in it. Avoid using strong soaps, jewelry cleaner liquids or other cleaners as most of these are not compatible with the oil treatment of Emeralds. Cleaning should be done no more frequently than is necessary, and never more than several times a year. After many years of wear, you may wish to have your Emerald re-oiled. Most local Jewelers can provide this service.