In people's jewelry luxury goods, diamonds refer to polished diamonds, which are also symbols of love and loyalty. People are curious about the reasons for the formation of diamonds. Let me explain to you in detail how diamonds are formed. The reason for the formation of diamonds The structural characteristics of diamonds: diamonds are made of carbon, which is a crystal with a hardness of 10. It is the hardest natural mineral in nature, with a density of 3. 53(0.0 1) g/cm3 with a refractive index of 2. 4 17, and the dispersion is 0. 044. It is the product of diamond cutting and polishing, and about one-fifth of the diamond minerals can reach the gem level, which is called gem-grade diamond, and it is called "rough diamond" or "rough diamond" abroad. After the blank is cut and polished into a cut shape, it is called a bare drill, and it is called a finished drill or a polished drill abroad. The English name Diamond comes from the Greek word amount, which means "hard, inviolable and invincible". Both diamond and graphite are made of carbon. Diamond and graphite are formed under different temperature and pressure conditions, and they can be transformed into each other under the change of temperature and pressure conditions. Diamond belongs to cubic crystal with hardness 10, and graphite belongs to hexagonal crystal with hardness 1. They have different crystal structures and are two homogeneous polymorphs of crystalline carbon. Only under certain pressure and temperature can carbon crystallize into diamond. Formation of diamonds: The earliest natural diamonds were formed in the earth, with the temperature of 900- 1600℃ and the pressure of (4.5-6)× 109Pa, which is equivalent to the depth of underground 130-200km. Theoretically, diamonds can be formed at any time as long as the conditions are met. Most of the diamonds mined at present were formed 3.3 billion years ago,12-1700 million years ago. The carbon that forms diamonds comes from molten magma in the mantle or crustal movement. Carbon belts in the earth's crust gather in the depths of the earth and crystallize into diamonds under suitable conditions. There is also an external way to produce diamonds. When meteorites hit the mainland, instantaneous high temperature and high pressure may also produce diamonds. However, the diamonds produced in this way are often small in size and poor in quality, and generally have no economic value, so they cannot be used as diamonds for jewelry processing. Discovery of diamonds: Diamonds were first discovered in India. With people's desire for diamonds, the exploration and mining of diamonds are becoming more and more popular. Diamond deposits are divided into primary ore and secondary ore. Primary ore is produced by the geological movement of the earth. Earthquakes and volcanic activities bring diamond-rich minerals to the surface or near the surface, most of which are kimberlite and lamprophyre rich in diamond, as well as fillers near the crater and root sediments in rock walls and bedrock. Under the action of nature, secondary ore is transported and deposited by primary ore. Most of them are washed away by weathering and rain, and remain on hillsides, rivers and coasts to form sediments, mostly placers. This is roughly how diamonds are formed and discovered, unlike precious metals such as gold. Since 2 1 century, the price of diamonds has kept a steady growth trend and gradually became the first choice of investors. Identification method of diamonds Simple identification method of diamonds: You need a magnifying glass of 10-20 times to make some simple observations. Observe the waist of the diamond. This is the best way to grind the waist with sand. Because diamonds are harder than any imitations, there will be no fine lines like imitations. The waist of a diamond is granular. Diamonds are harder than imitations, and the facets of imitations are often blunt than diamonds, but the facets of diamonds must be sharp. Because diamonds are harder than imitations, the faceted edges of imitations tend to wear out. If a diamond has a natural surface, it has a chance to find its unique "triangular growth line" on the natural surface. If a diamond is broken, its appearance is usually stepped, while the imitation is curved or shell-shaped. Hardness check diamonds are the hardest natural substances known, and nothing can mark them. If you can, it's not a diamond. The heat conduction test breathes when debating diamonds and other similar items. If it is a diamond, the water mist condensed on its surface should evaporate faster than the water mist on other items. This is because diamonds have high thermal conductivity. Observation method Reflected light With a magnifying glass, it can be observed that the waist of the diamond is very fine and frosted, and the reflected light shines. This characteristic of diamonds is unique. Looking at the growth point under a magnifying glass, there are often grooves and triangular growth points on the crystal face of real diamonds, but there are three kinds of fakes: ① ordinary glass with alumina is easy to get into the wrong place because the refractive index and dispersion increase, but the hardness is low. (2) Imitated by chemically synthesized sapphire and colorless spinel, the hardness is similar, but the refractive index is low and has birefringence, and the double image can be seen under a magnifying glass. The chemical composition of pencils is carbon, just like diamonds, but the physical structure is different, so many people use pencils to detect the authenticity of diamonds, which is a practical and effective method. When identifying, they must first wet the diamond with water, and then draw a line gently with a pencil. On the crystal face of a real diamond, there is no trace where the pencil crosses, but if it is not a diamond, but a material such as glass and crystal, it will leave a trace on the surface. Generally, it will be marked with a pencil to identify the authenticity of diamonds. This product has high hardness and good refraction, but it will reflect more colored light when rotating, which is obviously different from the genuine product that only reflects weak yellow and blue light when rotating. Diamond cutting procedure A rough stone looks unremarkable, and it must be carefully cut, polished and processed to become a shiny diamond that we are used to. Therefore, the turning of diamonds directly affects the value of diamonds, which is described in detail below. Of course, the ideal cutting effect is to keep the maximum weight of the diamond, minimize the defects, fully display the beauty of the diamond and make it shine. The general cutting process includes the following steps: 1. Scribing: This is the first step in diamond cutting. First, check the rough and mark the diamond surface. The people who do this job are experienced and proficient in processing technology. The ultimate goal is to produce the largest, cleanest and most perfect diamond, so as to reflect the value of diamonds as high as possible. The scribe must pay attention to two points: keep the maximum weight and minimize inclusions. The scriber studied the structure of the drill blank with a magnifying glass. If it is a big diamond, this work may take several months, while for a common rough diamond, it will take several minutes. However, no matter how small the original stone is, every diamond must be carefully examined before a correct judgment can be made. The scribe marked the blank with Indian ink, indicating that the blank should be divided along this line. Usually, lines are drawn as far as possible along the natural grain direction of diamonds. The slitting knife puts the blank with drawn lines on the bracket, then cuts a dent along the longitudinal tangent with another diamond, and then puts a square knife on the dent and hits it hard by hand. The diamond will split into two or more pieces along the grain direction. Sawing most diamonds is not suitable for chopping, so it needs to be cut with a saw. Because only diamonds can cut diamonds, the saw blade is a phosphor bronze disc with diamond powder and lubricant coated on the edge. The diamond is fixed on the fixture, and the saw disc rotates at high speed to cut the diamond. Modern laser technology is introduced into diamond cutting, which greatly improves the machining efficiency of the drill blank. The sawed or cut diamonds with the required shape are sent to the rounding part for rounding and shaping, that is, according to the design requirements, the diamonds are made into common cut flower shapes such as round, heart-shaped, oval, pointed and emerald, or other special shapes. Because diamonds are the hardest natural substance recognized by human beings so far, only diamonds can polish diamonds, and the hardness of diamonds is slightly different in all directions. Therefore, it is necessary to master the basic forms of diamonds by experience: trihedron, octahedron, dodecahedron and crystal characteristics. The general method is to rotate the drill blank at high speed on the lathe, and then round the rotating drill blank with the diamond on the other arm. Polishing on a cast iron disk coated with diamond powder and lubricating oil, all facets (facets) are rotated, making the diamond shine. Usually, the grinding process is to make 8 large faces at the bottom, and then 16 small faces. It has a sharp bottom and 25 facets, from which extend triangular facets, kite facets, waist facets and ***33 facets. This round diamond has 58 facets, or 57 facets if there are no pointed facets. Not every drill blank has to go through all the above processes, which depends on the characteristics of the drill blank and the goal to be achieved. For example, a "flat" diamond blank may not need to be divided, or an emerald diamond may not need to be rounded. However, for any rough diamond, there are two essential processes, namely "scoring", "chipping" and polishing. The position and angle of the petal surface produced by a finely crafted diamond are accurately calculated, which makes the diamond the brightest. With the development of science and technology, the introduction of laser technology and computer technology can make the design and cutting of drill blanks more accurate. The chemical composition of diamonds The chemical composition of diamonds is carbon, which is the only single element in gems and belongs to the equiaxed crystal system. It often contains 0.05%-0.2% impurity elements, of which N and B are the most important, and their existence is related to the types and properties of diamonds. Most crystals are octahedron, rhombic dodecahedron, tetrahedron and their aggregates. Pure diamonds are colorless and transparent, showing different colors due to the mixing of trace elements. Strong diamond luster. The refractive index is 2.4 17 and the dispersion is moderate, which is 0.044. An isotropic object. The thermal conductivity is 0.35 calories/cm/sec/degree. Tested with a thermal conductivity meter, the response is the most sensitive. The hardness is 10, which is the hardest mineral known at present. Its absolute hardness is 1 0,000 times that of corundum and 1 0,50 times that of corundum. It is afraid of a heavy blow, and it will be cut after a heavy blow. A group of completely cracked. The density is 3.52g/cm3. Diamonds are luminous, and when exposed to the sun, they give off a faint cyan phosphorescence at night. X-ray irradiation will emit sky-blue fluorescence. The chemical properties of diamond are very stable, and it is not easy to dissolve in acid and alkali at room temperature, and acid and alkali will not affect it. The difference between diamonds and similar gems and synthetic diamonds. Common substitutes or counterfeits in gem market include colorless gemstones, colorless spinel, cubic zirconia, strontium titanate, yttrium aluminum garnet, yttrium gallium garnet, artificial rutile and so on. Synthetic diamonds were first developed by Japan in 1955, but they were not mass-produced. Synthetic diamonds are rare in the market because they are more expensive than natural diamonds. Diamonds can be distinguished from similar gems by their unique hardness, density, dispersion and refractive index. For example, diamond-like cubic zirconia is colorless, with strong dispersibility (0.060), strong luster, high density of 5.8g/cm3 and heavy hand feeling. Yttrium garnet has a soft dispersity, so it is difficult to distinguish it from diamonds with naked eyes. Look at how diamonds are formed. Look at: 1. How is the gold mine formed? 2. How is the moonstone formed? 3. How is lightning formed? 4. How is the lagoon formed? 5. How are the pearls of shells formed?