Identification of Ruby "Ten Hong Jiu Cracks" in natural gemstones, and natural rubies without any flaws and cracks are extremely rare. Artificial rubies have the same color, few internal defects or crystal inclusions, and are clean and large. As a precious gem, natural rubies over 3 carats are very rare in the market. If you encounter a big ruby, you should pay attention, because the value of natural ruby is thousands of times higher than that of artificial ruby. A little carelessness will "take medicine." Natural ruby has a strong "dichroism". The so-called dichroism means that there are two colors of red and orange red from different directions. If there is only one color, it may be red spinel, garnet or red glass. Red spinel and natural ruby are very similar, and they are most easily confused, so be very careful. [1] Identification of diamonds: diamonds are the hardest natural substances. A diamond can carve any other gem, but no other gem can carve a diamond. You can also use the "standard hardness tester" to score, and any hardness below 9 degrees is a fake diamond. Diamonds are also lipophilic. If you draw a line on the surface of a diamond with a pen, it will become a continuous straight line, while other gems will break intermittently. The above methods have certain reference value for identifying diamonds. You can also observe it through a magnifying glass with a magnification of 10. Under the magnifying glass of 10 times, most diamonds can see defects, such as triangular growth lines, and the diamond surface has "red, orange and blue" fire light. Radiant. The most accurate and reliable method is to measure the thermal conductivity data with a "thermal conductivity meter" to distinguish between genuine and fake diamonds, but the "thermal conductivity meter" is expensive. Identification of sapphire The color of natural sapphire is often uneven, and most of them have a flat growth line. Artificial sapphires are of the same color, and their growth lines are arc-shaped strips, and they are often breadcrumb-shaped or beaded bubbles in the body. Natural sapphire also has obvious dichroism, one direction is blue, and the other direction is blue-green. Other gemstones are different in color from natural sapphires and can be distinguished. In addition, the simplest method can be hardness measurement. Natural sapphires can carve traces on topaz, while other sapphires are difficult to carve traces on topaz. Therefore, when buying jewelry, if there is no instrument around, as long as there is a topaz, sometimes some problems can be solved. Identification of Emerald The difference between emeralds and similar natural green gems, synthetic emeralds and fakes. Similar natural green gems include fluorite, green tourmaline, apatite, jadeite, green sapphire and garnet containing chromium, vanadium, calcium and aluminum; Artificial emeralds and imitations include synthetic emeralds, beryl, foil-lined emeralds and oiled emeralds. The differences are as follows: fluorite, blue-green, isotropic, low hardness 4, density 3. 18 g/cm3, larger than emerald, light blue fluorescence. Green tourmaline and dark blue green tourmaline become pure green after treatment, with obvious dichroism, high birefringence, 0. 18 and high density. Apatite, light green apatite, with blue hue, small hardness of 5, large refractive index of 1.632- 1.667, and phosphorescence under ultraviolet light. Emeralds, high-quality translucent emeralds are more like emeralds, but emeralds have a fiber interwoven structure with finer fibers, which emeralds do not have. In addition, garnet containing Cr, V, Ca and Al [2] is emerald green, isotropic and has a strong diamond luster. Emerald is synthesized artificially by flux growth method and hydrothermal method, with rich colors, strong red fluorescence under ultraviolet light and bright red under color filter. There are also beryl three-layer stones, foil-lined emeralds, oil-colored emeralds, etc., which can be distinguished from emeralds after careful observation and identification. Identification of jadeite Some people say that a piece of green jadeite is irradiated with Dow filter. If it turns red, it can be said that this jade is dyed, and if it does not change color, it is its true color. This statement is mechanical and parrot-learned. Dow filter is a kind of filter that only allows red light and orange light to pass through. The fuel used for jadeite dyeing usually contains chromium salt. It will emit red light when its concentration is high, and it will appear red under Dow filter. However, if the dyed color is not deep, the concentration of chromium salt is not high, and it is red under Dow filter, which is not easy to observe. In addition, natural green jadeite sometimes contains a small amount of substances that emit red light. When observing green jadeite with Dow color filter, it needs to be carefully analyzed, which will be indicative and cannot make a conclusive judgment. So what's the difference between natural green and dyed green of jadeite? I know that jadeite is dyed, and natural jadeite has three colors: green, white and purple, because the particles that make up jadeite have three colors: green, white and purple. Therefore, when we look at the color of a natural jadeite, its color and crystal are inseparable, while the original crystal of dyed jadeite is colorless. The dye that enters jadeite through impregnation permeates along the intergranular cracks or some tiny cracks of the crystal, so there is an obvious boundary between color and crystal. Identification of Cat's Eye In recent years, there is a kind of glass fiber cat's eye ring on the market, which is embedded in a gold or silver ring, making it impossible to tell the true from the false. The identification method is that when the torus is rotated, several light bands can appear at the arc top of the fake cat's eye at the same time, while there is only one real cat's eye. The fake cat's eye eyeliner is rigid, while the real cat's eye eyeliner is flexible. True cat's eyes are mostly brownish yellow or light green, while fake cat's eyes are varied in color, including red, blue and green. Golden emeralds are second only to diamonds and red sapphires in hardness. Golden emeralds and various changeable stones and opals are not only very beautiful, but also very expensive, because they are extremely rare. Opal is a color-changing effect of emeralds with developed vacuum inclusions after cutting by Kapson. The identification of opal can be divided into black opal, white opal and yellow opal according to its color, of which black opal has the highest price. In order to improve the low-priced white or yellow opal, some people change its color artificially and become "black opal" in order to make high profits. The main method is to boil with sugar or inject plastic to make the white opal black. The identification method is that the specific gravity of opal is obviously different after boiling sugar or injection molding, and the specific gravity value becomes lighter when tested in water. The heating needle can also be used to test the opal of injection. Natural opal can't be pierced by hot needles, but injected opal can be pierced, and it will produce the smell of plastic melting. Identification of Tourmaline Tourmaline is a kind of intermediate gemstone, but because pink and bright blue tourmalines are more expensive, there are also imitations. There are two common imitations, one is artificial coloring with colorless tourmaline; One is made of red glass. The identification method is that the real tourmaline often has obvious dichroism and can be seen as a ghost; Tubular inclusions or cotton wool can be seen in the body, and the crystal cross section is curved triangle. These characteristics are not possessed by imitations. The tourmaline dyed by workers is not difficult to identify because its color is dull and there is no "treasure light" of natural tourmaline. Identification of crystalline rock crystals is clear and transparent, often containing cloud-like, star-like or flocculent gas-liquid inclusions, often with microcracks. In addition, the rock crystal is polarized, and you can see the phenomenon of twin crystals, such as a crystal ball. Looking down from the top, there will be a double image. Synthetic crystal or glass products are uniform and pure in the body, without cracks, and often have small bubbles inside. Looking down at the sphere, you can't see the ghost of the line below. Through touch recognition, we can feel that the proportion of synthetic crystals is greater than that of rock crystals; Crystal stone feels cold and glass feels warm. Identification of Olivine Olivine is a kind of low-grade gem with yellow green and olive color. The most common counterfeit olivine on the market is made of stained glass. The main difference between the two is that olivine has obvious "double shadow", while glass does not; Crystal inclusions are often seen in olivine, and only bubbles are contained in glass. Olivine has a specific gravity of 3.5 and a hardness of 7, which is greater than that of glass (2.6) and hardness (6). There are natural pearls and cultured pearls, and cultured pearls are divided into seawater pearls and freshwater pearls. Natural pearls are low in output and expensive; Moreover, cultured pearls can be produced in large quantities, so the price is much lower. The main difference between them is that natural pearls and cultured pearls have no nuclei. The inner core of natural pearls is often just some sand or parasites, or even no inner core. However, the inner core of cultured pearls is artificially made large round beads, so the outer coating is thin. On the body surface, natural pearls rarely roll because of their random growth environment and poor roundness. The inner core of cultured pearls is round, so the roundness of pearls is better. Natural pearls are transparent because of their long growth time, delicate texture, thick nacre, smooth skin and few "convex bubbles". The cultured pearls are thin in layer, rough in texture, "waxy" in luster, and have some uneven "bubbles" on the surface, so the transparency is poor.