Crystal belongs to low-grade jewelry!
Three elements of jewelry: beauty, rarity and durability! This is what they have in common! Among them, diamond also has the highest hardness, strong refraction and high dispersion.
So diamonds are the most precious gems!
Diamond is a natural mineral with equiaxed crystal system, which is almost completely crystallized from carbon atoms. Its mineralogical name is diamond. Diamond is the title of gem-grade diamond. ? Physical and chemical properties of diamonds:? Diamonds often contain impurities such as silicon, aluminum, calcium, magnesium, manganese, titanium, chromium and nitrogen. Its Mohs hardness is 10, specific gravity is 3.52, refractive index is 2.4 17, dispersion is 0.044, compressive strength is 10Kpa, thermal conductivity is 7- 14 w/(cm.k) at 300K, and it has diamond luster. Chemical properties are very stable, even at high temperature, it does not react with corrosive media such as strong acid and aqua regia. ? Characteristics of diamonds:? Diamonds are formed in the depths of the earth under complicated conditions such as high pressure and high temperature. ? (1) is the hardest of all substances in the world. ? (2) Very high dispersion and refractive index. ? (3) Super chemical stability and rare and non-renewable characteristics. ? (4) Diamonds are gems with the strictest quality evaluation and the most international evaluation criteria. These characteristics make diamond the most beautiful and precious gem endowed by nature, and it is known as the "king of gems". ? The symbol of diamond:? Humans have discovered and used diamonds for only a few hundred years, accompanied by myths and legends, religious worship and fear. 1477 August to 17 August, Austrian Maximilian I proposed to French Princesse Marie and put a diamond-encrusted ring on his ring finger. Since then, diamonds have become a symbol of love and loyalty of all mankind. It is because of Marilyn Monroe's song "Diamonds, Women's Best Friends" that it is famous all over the world.
Similarities and differences between crystal and agate
The chemical composition of crystal and agate is silica, but there are still some differences between them. Crystal is a single crystal, crystal is usually a crystal, and agate is a polycrystalline aggregate. Under the electron microscope, agate is composed of countless tiny silicon dioxide crystals, so agate is usually translucent, while crystal is transparent. Many times, the two will be reborn, forming a crystal cave sold by crystal shops.
People generally judge the quality and economic value of agate by naked eye identification. Although modern technology is developed and there are many jade identification instruments, it is very inconvenient to use these instruments in the transaction process. Secondly, it can't solve the problem. The reason is very simple, and it will be limited by the environment. If we judge the quality and economic value of agate, the instrument will be useless. It is impossible to carry out complex instrument operation at the trading site, so naked eye identification is always an extremely important method. There are many kinds of agates, known as "1000 kinds of agates and 10000 kinds of jade", so there are many identification methods. Usually, the grading standards are stripes, colors, transparency, cracks, impurities, sand cores and block weight. Except water bile agate, which is the most precious, it is generally best to match harmonious and pretty raw materials.
Generally speaking, agate quality appraisal and economic value evaluation are mainly divided into the following categories:
1, super: beautiful stripes; Pure and bright red, blue, purple and pink; Good transparency, that is, translucent; No cracks, sand cores and impurities; The weight of wood blocks is about 5 kg or more.
2, level 1: beautiful stripes; Pure and bright red, blue, purple and pink; Good transparency, that is, translucent; No cracks, sand cores and impurities; This block weighs about 2-5 kilograms.
Grade 3 and 2: beautiful stripes; Pure and bright red, blue, purple and pink; Good transparency, that is, translucent; No cracks, sand cores and impurities; The weight of the block is about 0.5-2 kg.
4, level 3: beautiful stripes; Pure and bright red, blue, purple and pink; Good transparency, that is, translucent; No cracks, sand cores and impurities; The weight of the block is about 0.5 kg or less.
The above aspects are the methods to identify the quality of real agate. In addition, there are a lot of fake agates on the market at present. The main products are synthetic agate, such as glass, plastic and stone. Although its texture and color are comparable to those of natural agate, it has no economic value. Sellers are delusional, and experts will sneer at it after reading it. Therefore, lovers should be careful when they want to collect or appreciate it. The main identification methods are:
1. Pattern and color: the real agate is bright and bright, while the fake agate is poor in color and light, and the contrast between them is obvious. Natural agate has distinct colors and obvious stripe patterns, while imitation fake agate is mostly bright and uniform, giving people a sense of authenticity.
2, texture: fake agate is mostly stone imitation, softer than real agate. Emerald can be used to draw traces on fake agate, but it really can't be drawn. There are few defects on the surface of real agate, and there are more inferior ones.
3. Transparency: The transparency of real agate is not as good as that of synthetic agate, which is a little messy. Some can see natural waterlines or "clouds", while synthetic agate has good transparency and is as transparent as a glass ball.
4. Weight: Real agate jewelry is heavier than synthetic agate jewelry.
5, temperature: real agate is warm in winter and cool in summer, while synthetic agate changes with the external temperature, it becomes hot when it is hot, and it becomes cold when it is cold.
How is jadeite formed? There are many magical legends circulating among the people; Geologists used to think it was a mystery. Some people think that jadeite, like diamonds, is crystallized under high temperature and high pressure of several thousand degrees deep in the earth's crust, but it is not. Many geophysicists in the United States have done a lot of simulation experiments in the laboratory, and combined with the actual situation of discovering jadeite deposits all over the world, they think that jadeite was not formed at high temperature, but metamorphic at low temperature and extremely high pressure.
Ichiro Shachuan, a professor at Tohoku University in Japan, pointed out in the book Talking about Gems (published in 1983) that jadeite was formed at 10,000 atmospheres and relatively low temperature (200-300℃). We know that the deeper the temperature, the greater the pressure from the surface of the earth to the depths. But jadeite is crystallized at low temperature and high pressure, and of course it can't be in a deeper part. So where does the high pressure come from?
It has been proved that this high pressure is caused by the compressive force produced by crustal movement. All jadeite deposits are distributed in areas with strong crustal movement.
Another factor is that there are igneous intrusions (intermediate basic rocks) containing albite where jadeite is found. The chemical composition of albite is NaAlSi3O8, so it can be inferred that jadeite is formed by desilication of albite-bearing rocks at low temperature and high pressure.
If you want to be a super jade-jade, you must also meet the following conditions. The surrounding rock of jadeite must be high in magnesium, calcium and iron. The jadeite produced in this environment is purer, and the bottom is not gray without iron. Although iron is low, there is still iron. If jadeite is pure and free of impurities, it must be produced under strong reducing conditions, that is, reducing environment. Because in the oxygen-deficient environment, the Fe contained in it will form magnetite and precipitate out, instead of entering the crystal lattice of jadeite, which can correct the emerald green. In addition, after the formation of jadeite, there must be geological processes and many strong hydrothermal activities, and jadeite should be transformed into super jadeite with green, good water quality and pure bottom. The color formation process of jadeite is accompanied by hydrothermal activity, which is a multi-stage color formation process with different intensities. Moreover, the chromogenic elements that slowly decompose into chromium ions need to be at 150-300℃ for a long time, and the optimal temperature is about 2 12℃, so that chromium ions can enter the crystal lattice uniformly and continuously, and the emerald green generated under this condition is very uniform. After the super jadeite is completely produced, there can be no large geological tectonic movement, otherwise cracks with different sizes and directions will occur, which will affect the quality. It is difficult to meet all the above conditions at the same time, which is also the reason why super jadeite is scarce.
That's all I know,