Emerald, known as the king of emeralds, is a precious gem (the birthstone of May) and one of the four precious gems recognized by the international jewelry industry (red, blue, emerald and DIA). Because of its unique green color, unique charm and magical legends, it is favored by Westerners and more and more by Chinese people recently. Among many silicate minerals, emerald is the most attractive color, so it is very popular.
Physical and chemical composition
Emerald is a silicate containing beryllium aluminum with the molecular formula Be3Al2[Si6O18], which belongs to the most "noble" member of the beryl family. It belongs to the hexagonal crystal system. The single crystals are hexagonal pillars, hexagonal double cones, and mostly rectangular pillars. The aggregates are granular, massive, etc. Emerald green, glass luster, transparent to translucent. The refractive index is 1.564-1.602, the birefringence is 0.005-0.009, and the pleochroism is not obvious. Heterogeneous body. The hardness is 7.5, and the density is 2.63-2.90 g/cm3. Incomplete cleavage, conchoidal fracture. With brittleness. Under X-ray irradiation, emeralds emit weak pure red fluorescence.
The benefits and functions of emerald
1. Emerald also has a soothing effect, can relieve people's tension, maintain a happy and relaxed mood, and have an open mind. At the same time, it contains a lot of trace elements inside, which can be continuously absorbed by the human body during the long-term wearing process, promote metabolism, and play a good health effect. All in all, emeralds can not only play a good decorative effect, but also bring many benefits to the wearer on the psychological and physical levels.
2. Since its discovery by humans, emeralds have been regarded as having the magical power to exorcise evil spirits. People use emeralds as amulets, anti-evil objects or religious ornaments. It is believed that wearing them can resist the invasion of snakes and beasts.
3. Emeralds are very ancient gems. They were used as jewelry in the ancient Egyptian era. Wearing emeralds for a long time can also calm the wearer's mind and give the wearer a peaceful mind.
4. Emerald's chemical name is: beryllium aluminum silicate, which belongs to the beryl family. The most abundant chemical elements are chromium and vanadium, and emeralds are formed because part of "aluminum" is replaced by "chromium". From a chemical point of view, "chromium" and "aluminum" cannot be combined. Therefore, this replacement reaction needs to be carried out under extremely special and extremely complicated geological conditions. The chromium and vanadium elements rich in emeralds are both essential trace elements for the human body.
How to identify emeralds
1.Color: Generally, those with no variegated color or a little bluish tint are the best products, and the green with grayish quality is poor. Because its color directly determines its price, some illegal businesses use dyeing and coating to make the color darker green. Genuine emeralds are often single-color green, transparent or semi-transparent. Because of their low dispersion value (0.014) and the cover of darker body color, there is usually no "fire color" visually, that is, no colored light.
2. Microscopic examination: Observed by Charles filter, the general Colombian emeralds appear red under the filter, while the South African emeralds still appear green, but the synthetic emeralds are darker than natural emeralds under the filter. Therefore, when we use the filter to observe, if the color of the gem is found to be unusually bright, we need to be vigilant and use some other methods to check its authenticity.
3. Colorless oil immersion is extremely common for emeralds. At present, almost 90% of emeralds have white oil immersion, which is also recognized by international jewelers. Therefore, emeralds soaked in white oil can also be regarded as natural emeralds. A credible appraisal will mark the amount of immersion oil on the remarks to let consumers know the situation clearly. But if it has been immersed in green oil, it is considered to have been optimized, and it is a fraud.
4. Identification of dyeing: (1) Heat the gemstone slightly, and wipe it with lens cleaning paper or white paper. If there are pigment stains on the paper, it is dyed. (2) Use an ultraviolet fluorescent lamp to irradiate, if a lot of fluorescence appears on the gemstone, it is a dyed gemstone.
5.Two kinds of coating treatments: (1) Substrate treatment: If the gemstones purchased are in the form of matting, you need to pay attention to the bottom coating treatment. A magnifying glass can be used to inspect the lower part of the mosaic surface. If there are seams or a lot of air bubbles, it is likely that the film has been used. If the film is found to fall off or wrinkle, there must be a coating treatment. (2) Surface epiphytic treatment: Observed by immersion in water, it is found that the color at the edges and corners is obviously concentrated, and the color of the surface is deep and the internal or surface reticular cracks are more obvious, so coating may be used.
6. Fill the bowl with clear water and put the gems in the bowl, which can make the whole bowl appear faintly green, which is true emeralds.
Put the emeralds to be identified in a copper basin, surround it with paper, and light the white paper with fire. If the fire turns green, it is a true emerald.
Prepare a pot of red fire charcoal, put the gemstones to be identified into the fire charcoal, and the charcoal smells and extinguishes immediately, it is a true emerald.