Definition
Mohs scale hardness 7.5 to 8
The mineral beryl (Be3Al2(SiO3)6) variation known as emerald is a gemstone that is occasionally tinted green with vanadium or chromium in trace proportions. On the Mohs scale, beryl is rated as 7.5-8 hard. Because of the high inclusion level of the majority of emeralds, their toughness (resistance to breaking) is typically rated as low. A cyclosilicate, emerald is.
Color, clarity, cut, and carat weight are the four fundamental criteria used to evaluate emeralds, like other colored gemstones. In grading colored gemstones, color is typically by far the most significant factor. Nonetheless, clarity is ranked as a close second in the grading of emeralds. For an emerald to be regarded as a top gemstone, it must have a high degree of transparency in addition to the pure, lush green colour specified below. The traditional "big four" gems are sapphire, diamond, ruby, and this member of the beryl family.
Color
The three parts of color are hue, saturation, and tone. While green always being the predominant color, emeralds may also be found in yellow-green, blue-green, and other colors. Normal secondary colors in emeralds include yellow and blue. The term "emerald" only refers to stones with a medium to dark tone; gems with lighter tones are referred to as "green beryl" instead. On a scale from 0% tone, which is colorless, to 100% tone, which is impenetrable black, the best emeralds have around 75% tone. Moreover, a high-quality emerald will be saturated with a vibrant colour (vivid). A dull green hue is a grayish-green hue, which is the typical saturation modifier or mask seen in emeralds.
Clarity
The inclusions and surface-breaking fractures in emeralds are often abundant. Emeralds are evaluated by eye, as opposed to diamonds, which are assessed using the loupe standard (10x magnification). So, if an emerald is perfect, it has no obvious inclusions to the eye (assuming normal visual acuity). Although stones without surface-breaking cracks are very uncommon, practically all emeralds have been treated (oiled) to increase their apparent clarity. Because to its mossy look, inclusions and cracks inside emeralds are occasionally referred to as jardin (French for garden). Each emerald's imperfections are distinctive, and you may use them to pinpoint a specific stone. The most expensive stones are those that are eye-clean and have a main green color that is as bright as the one described above, with no more than 15% of any secondary color or combination (either blue or yellow) with a medium-dark tone. Cutting emeralds in cabochon form rather than faceted forms is motivated by the relative non-uniformity. Most frequently, faceted emeralds are cut into an oval shape or into their distinctive "emerald cut," which is a rectangular shape with facets along the top edge.
Treatments
In order to fill in surface-reaching fissures and enhance clarity and stability, most emeralds undergo post-lapidary oiling. Similar in refractive index to cedar oil, it is frequently employed in this extensively utilized method. Other liquids are also employed, such as synthetic oils and polymers like Opticon with refractive indices that are comparable to that of emeralds. Epoxy resins are frequently used to fix the less costly emeralds because they are efficient at filling fractured stones. These procedures are often performed in a vacuum chamber with low heat to allow the stone's pores to open up and better absorb the fracture-filling material. Even though oil-treated emeralds are substantially less valuable than untreated emeralds of comparable quality, using oil is customary and well accepted in the gem industry. Furthermore required for untreated emeralds is a certificate from a recognized, independent gemology lab. Alternative therapies are not permitted in the industry, such as the usage of green-tinted oil. There are four grades for gems: none, minor, moderate, and greatly enhanced. These divisions represent degrees of improvement, not clarity. On the enhancement scale, a diamond with a grade of none may nevertheless have obvious inclusions. These standards are applied differently by laboratories. Some gemologists believe that enhancement already exists when oil or polymers are present. If the oil is there but does not enhance the appearance of the gemstone, others may dismiss it.
Origins
Once the Colombian reserves were discovered, mining in Egypt was abandoned. Today, all that is left are the ruins. Depending on the year, source, and grade, Colombia produces between 50 and 95 percent of the world's emeralds. Colombia's emerald output has dramatically expanded in the previous ten years, rising by 78% from 2000 to 2010. Muzo, Coscuez, and Chivor are the three major emerald mining regions of Colombia. Colombia is home to the uncommon "trapiche" emeralds, which are identified by ray-like spokes of black impurities. In 2004, 20% of the world's output of gem-quality stones came from Zambia, the second-largest producer in the world, namely from deposits in the Kafubu River area (Kagem Mines), which are located approximately 45 kilometers (28 miles) southwest of Kitwe. 3.74 tons of emeralds were produced by the Kagem Mines in the first half of 2011. The world is home to many countries where emeralds can be found, including Afghanistan, Australia, Austria, Brazil, Bulgaria, Cambodia, Canada, China, Egypt, Ethiopia, France, Germany, India, Kazakhstan, Madagascar, Mozambique, Namibia, Nigeria, Norway, Pakistan, Russia, Somalia, South Africa, Spain, Switzerland, Tanzania, the United States, Zambia, and Zimbabwe. Emeralds have been discovered in the US states of Connecticut, Montana, Nevada, North Carolina, and South Carolina. In the Canadian Yukon Territory, emeralds were found in 1997.