Cubic f lattice
The theme is C (0
0) and C (1/4
1/4
1/4). In diamond crystals, carbon atoms are interconnected by tetrahedral bonds, forming an infinite three-dimensional skeleton, which is a typical atomic crystal. Each carbon atom forms a valence bond with the other four carbon atoms through SP3 hybrid orbitals, forming a regular tetrahedron. Because the C-C bond in diamond is very strong, all valence electrons participate in the formation of valence bond, and there are no free electrons, so diamond is not only hard, but also has a very high melting point and is not conductive. In industry, diamonds are mainly used to make probes and abrasives for drilling, and also used to make high-grade decorations such as jewelry with complete modeling, which is very expensive. [Editor] Physical properties The Mohs hardness of diamond is10; Because of the highest hardness, diamond powder or laser (such as 532nm or 1064nm wavelength laser) must be used for diamond cutting. The density of diamond is 3.52g/cm3, the refractive index is 2.4 17, and the dispersion rate is 0.044. [Editor] Ornamental diamonds, because of their high refractive index, shine in the light and become ladies' favorite gems, which are called diamonds. Huge beautiful diamonds may be priceless. Dark diamonds are more expensive. When diamonds are blue, green or pink, they are very rare, while when the color is dark and bright, the price is high; At present, the most expensive colored diamond are those with rich red. Diamonds are divided into type I and type II, mainly depending on whether they contain N elements: type I contains N elements; Type II does not include. The blue diamond is type B, which is a semiconductor. [Editor] Industrial use Because of the extremely high hardness of diamonds, scientists will use high temperature and high pressure to make diamond particles, which can be used in sandpaper, drilling and grinding tools, and can also be used to cut and depict other substances. [Editor] The traditional standard for determining the value of diamonds is the "4C" system, that is, card, color, clarity and cut. [Editor] Kaka, or carat, is the unit of quality of diamonds. One card is 200mg. According to legend, in the early days, the diamond was weighed by the fruit of carob tree, and one such fruit weighed about 200mg. Because the density of diamonds is basically the same, the heavier the diamond, the bigger the volume. The bigger the diamond, the rarer it is, and the higher the value of each card. The following table shows the price comparison in 2005. The card value of each card (USD) is 0.5 CARDS 3.
000 1
500 1.0 card 5
000 5
000 1.5 card 7
000 10
500 2.0 cards 10
000 20
000 3.0 card 15
000 45
000 5.0 cards, 20 cards
000 100
000[ Edit] Clarity depends on the number of defects in the diamond. Defects may be natural impurities or cracks. The number, location and size of defects will affect the rating. Only 20% of diamonds mined from diamond mines can become gems, and the rest can only be used for industrial purposes because of defects. Most of the 20% gem-grade diamonds contain visible defects. Diamonds above this level are more popular. As for the perfect diamond, it is rare, and it is called "museum-class" diamond. Usually, the size, quantity and distribution of internal and surface defects of diamonds and their influence on diamond luster are observed with a magnifying glass of 10 times, and graded. The general clarity classification is as follows: FL-"flawless", perfect. There are no flaws inside and outside under a magnifying glass of ten times. If-"immanent", immanent is immaculate. Under the magnifying glass of ten times, only the surface has slight flower marks. VVS 1
VVS 2-"very, very thin", very, very small. Defects that are difficult to see only under a ten-fold magnifying glass. The net crossover of VVS 1 is higher than VVS2. VS 1 and vs 2-"very thin", very small. Defects can be seen under a magnifying glass of ten times, but it is difficult for the naked eye to recognize them. The net crossing of VS 1 is higher than that of VS2. Si 1 and si2- "slight inclusions", small flaws, which may be visible to the naked eye. I 1
I2 and I3- "Imperfect" are flawed and visible to the naked eye. Under modern technology, some diamond defects can be repaired. However, the value of the restored diamond will be slightly lower. [Editor] The color of diamonds will be different due to chemical impurities. Completely pure diamonds should be transparent and colorless. A diamond's preference for different colors will affect its value. Most diamonds are yellow because they contain nitrogen atoms. The yellower the white diamond, the lower its value. But the price of pink or blue diamonds is higher. A strong preference for pink or blue diamonds can be priceless. The general method is to classify diamonds into different grades according to their yellowness, and compare the samples with the known color grades to determine that the D grade is the highest and the Z grade is the lowest. Colorless: d
E
F is almost colorless.
H
I
J light yellow: k
L
faint yellow
O
P
Q
R light yellow: s
T
U
V
W
X
Y
Z[ Editor] Cutting picture reference: upload.wikimedia/ * * */MONS/3/36/Diamond diamond ring (circular faceted cutting method) Cutting refers to how diamonds are cut into gems from the originally mined stones. Cutting is often the most influential indicator of diamond quality and value, but there is no single grading method. [Editor] Diamonds that have not been cut and polished will not shine brightly. The function of cutting is to cut the diamond into a shape that can reflect light to the maximum extent. 19 19 Mathematician Marcel Tolkowsky invented a cutting method that can make diamonds look the most brilliant from above. This cutting method is called round crystal, which is the most common round diamond. The general standard of this kind of diamond is 57 or 58 faces, 33 faces are in the crown, and 24 or 25 faces (that is, grinding the other face at the bottom tip) are below the waist. Shapes that do not belong to this kind of cutting are called fancy cutting, including square, pear and heart. 1977, Japanese Maofu developed the eight-heart and eight-arrow turning method for more than 20 years. In recent years, diamonds with eight hearts and eight arrows have become the mainstream of the market. Judging from the consumers' reaction and love in the market, diamonds with eight hearts and eight arrows are the best among diamonds. Most people agree that the diamond with eight hearts and eight arrows is a kind of excellent diamond, mainly because it has the following main characteristics: 1. Excellent brightness. 2. The fire color is excellent. 3. Excellent optical symmetry. 4. Excellent optical diameter. 5. Perfect and clear heart pattern. (1) Indicate the ideal lathe operator or super-ideal lathe operator in the market. This is the most beautiful diamond. This is a perfect diamond. Its beauty mainly comes from the "brightness" of the light reflected by gemstones and the "fire color" formed by the refraction of light through diamonds. There are mainly two turning conditions: 1. This diamond has excellent symmetry. 2. The rotation angle of the round diamond matches the pavilion angle to some extent. (2) Image analysis of eight hearts and eight arrows: a. Analyze the image of arrows: each arrow consists of an arrow and an arrow shaft. As shown in the figure, the main face of the pavilion consists of several sides of the diamond, namely, two sides and two short sides of the diamond.
The short side maps the image to form an arrow. B. Mental image analysis: Mental image is composed of two pavilion main faces, two upper waist facets and two lower waist facets. A complete heart is not only symmetrical, but also has a V-shaped gap in the middle. 3. Analysis of the image formation of eight hearts and eight arrows: Therefore, the first important factor in the formation of eight hearts and eight arrows diamond is the matching of the crown angle and pavilion angle of the diamond. Even diamonds with good symmetry need to form eight hearts and eight arrows.
This further shows that the requirements for forming eight-heart and eight-arrow graphics are not exactly the same as the 4C standard. Even within the ideal cutting range, the ratio of the crown angle to the pavilion angle of the diamond does not match, so the figure of the heart arrow cannot be formed. According to the optical path calculation of this diamond, Moscow State University
A diamond with eight hearts and eight arrows is observed in the corresponding crown angle and pavilion angle.
It is concluded that the light leakage is small when the figure with eight hearts and eight arrows appears.
When the light leakage becomes bigger, the figure of eight hearts and eight arrows disappears. [Editor] Diamonds with proper cutting quality are more beautiful than diamonds with the same weight and color but poor cutting. Judging whether the cutting is good or not depends on the various proportions of diamonds, the symmetry of all sides, various angles and so on. Sometimes the cutting angles of diamonds are different by several degrees, which will cause completely different effects. The cut diamond is usually only half the weight of the original stone. In order to keep the maximum weight of the diamond, or to avoid impurities in the original stone, some diamonds will sacrifice the perfect cut ratio when cutting. [Editor] In order to curb the trade of "blood diamonds", it is suggested to upgrade the "4C" system to "5C" system, and add a new standard of "morality" under the four standards to prove that diamonds are not used to finance wars and that there is no child labor in the process of drilling and mining with safety equipment. Under the new system, more than one diamond card will be accompanied by a computer chip containing mining and drilling photos. See blood diamond.
Reference: zh. *** /w/index？ Title =%E9%9 1%BD%E7%9F%B3 and variant =zh-
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Diamonds are made of carbon.
Diamond (scientific name) is one of the allotropes of carbon, and it is also a natural mineral material with the highest hardness and incomparable luster on the earth. It is hard, transparent and has high optical dispersion. High quality jewelry can be used, and low quality jewelry can be used for cutting in industry. Diamonds are not easy to wear, but only scratch other diamonds, and the same material should be scratched. Every year,/kloc-0.30 billion calories (26,000 kg) are mined, and at the same time/kloc-0.0 million kg is produced manually.
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Diamonds are crystals of carbon, which are formed at high temperature and high pressure.