Africa 1
Southern Africa is the main diamond producing area in the world, and South Africa, Angola, Zaire, Botswana and Namibia are all important diamond producing countries. So far, South Africa has discovered 350 kimberlite cones with an estimated diamond content of 250 million ct. Botswana is another important diamond producing area in Africa. So far, more than 200 kimberlite cones have been discovered, of which 465,438+0 is estimated to be 350 million ct.
2. Russia
Russia first discovered the primary diamond deposit in Yakutia, Siberia in 1954. So far, 450 kimberlite bodies have been discovered with an estimated diamond content of 250 million carats. World-famous rock pipes include Heping, Chenggong and Aihar. 1988 A new diamond mine was discovered in Geersk, Alhan, with an estimated reserve of about 250 million ct, 50% of which is gem-grade. At present, Russia is cooperating with the British company De Beers in exploration.
3. Australia and Canada
Kimberlite with diamonds was discovered in South Australia on 1972. 1979 The discovery of olivine-potassium-magnesium lamprophyre containing diamond is a breakthrough in diamond deposit science, because it is the first time in the world to find diamond in non-kimberlite rocks, which is of great significance. At present, more than 150 K-Mg lamprophyres have been found in northern Western Australia, especially in argyle, which is the richest and largest diamond-bearing rock mass in the world. Australia has become the country with the largest diamond production in the world, and its output has become the first in the world. Only in 1998, Australian diamonds reached 4 100 ct, but few of them reached the gem level.
1990, kimberlite-type diamond primary ore was first discovered in the lake area near the Arctic Circle, 360km northeast of Yale Neve, northwest Canada. At present, 5 1 kimberlite pipes have been found, most of which contain diamonds. There are five kinds of rock pipes with important economic value, and their diamonds are mainly colorless and transparent, with good quality. Gemstone diamonds account for 30% ~ 40%, with an average grade of 25 ct ~ 100 ct/ 100 t, and the estimated annual output can reach 4 million CT. The discovery of primary diamond deposits in northwest Canada is a major breakthrough in the world diamond history since 1990s.
4. Asia and China
In Asia, India is the first place to find diamonds in the world. Moreover, ancient famous big diamonds such as Mughal Dynasty (787ct), Mountain of Light (108.8ct), Regent (140ct) and orlov (189.6ct) were all produced here, but Indian diamonds are native. China is a country with less diamond resources in the world. 1950, the diamond placer with economic value was first discovered in Yuanjiang river basin, Hunan province. Low grade, scattered distribution, but good quality, gem-grade diamonds account for about 40%. In 1960s, primary diamond mines were discovered in Guizhou and Mengyin, Shandong. In the early 1970s, the largest primary diamond mine in China was discovered in southern Liaoning. The mine has large reserves and good quality, and the output of gem-grade diamonds is high, accounting for more than 50%. Shandong diamond primary ore has high grade and large reserves, but poor quality. Gem-grade diamonds account for about 65,438+02%, generally yellow, mainly industrial diamonds.
Think about a problem
First of all, is it right or wrong?
1. A light source with a color temperature of 4700 ~ 6500 K must be used to determine the color scale of diamonds.
2. Diamonds have fluorescence under long-wave ultraviolet lamp.
3. When grading the diamond color, if the measured diamond color is between two sample stones H and I, the sample color grade should be H. ..
4. When grading the diamond color, if the measured diamond is between two samples in color, it should be rated as a lower grade.
5. The indentation hardness of diamonds in different directions is the same.
6. The width of a diamond is 66% of the average diameter of the waist, which should be cut according to the national standard.
7. The thermal conductivity of diamond is the highest of all substances.
8. Diamonds are equiaxed minerals, so the hardness of different crystal faces is the same.
9. The light transmitted by diamonds is polarized light.
10. The refractive index of diamond can be determined by using CZ as a hemispherical refractometer.
1 1. The thermal conductivity meter can distinguish diamond from synthetic α-moissanite.
12. The sample showing diamond reaction on the thermal conductivity meter is not necessarily diamond.
13.x-ray fluorescence spectrometer can find out whether the diamond sample contains nitrogen.
14. Diamonds are natural gems with the highest dispersion value (dis. ).
Second, multiple-choice questions (65438+ 0 points for each question, ***25 points. Fill in the brackets after the question with the answer of your choice: a or b or c)
1. At present, the main producing areas of diamonds in China are: ()
A. Shandong, Hunan and Liaoning
B. Liaoning, Shandong and Jiangsu
C. Hunan, Hubei, Shandong
2. When identifying diamonds with a diamond pen, diamonds are used: ()
A. High thermal conductivity
B. High hardness
C. Good affinity
3. Which of the following instruments should be used to distinguish diamonds from synthetic diamonds: ()
A. thermal conductivity meter
B. spectroscope
C. infrared spectrometer
4. The natural blue color of diamonds is due to the trace elements contained in diamonds: ()
A. boron
B. Nitrogen
C. cobalt
5. The weight of cubic zirconia with the same volume as 1.76 carat diamond is: ()
A. 1.76 carats
B. 2.60 carats
C. 2.90 carats
6. The weight of a diamond is 1.538 carats, which should be expressed as: ()
A. 1.54ct and 1.53ct will do.
B. 1.54 carats
C. 1.53 carats
7. The natural yellow color of diamonds is due to the trace elements contained in diamonds: ()
A. boron
B. Nitrogen
C. cobalt
8. Diamonds under ultraviolet light: ()
A. all have fluorescence
B.it can be fluorescent.
C. no fluorescence.
9. Countries with the largest diamond production at present: ()
A. South Africa
B. Russia
C. Australia
10.365 nm diamond: ()
A. all have blue fluorescence
B.it may have yellow fluorescence.
C. green fluorescence is possible.
D. no fluorescence is allowed.
1 1. The diamond is: ()
A. Natural element minerals
B. it can be synthesized by hydrothermal method.
C. it is conformal to graphite.
D. the polymorphic variant with hexagonal system 2 H type is called hexagonal diamond
12. The cutting angle of diamonds is very strict, in order to make diamonds show the best ().
A. dizzy
B. color
C. huocai
D. discoloration
13. In the identification of diamond jewelry, a black inclusion is visible to the naked eye in the diamond table, and the clarity of the diamond should be ().
A. Right
B. international system of units of measurement
c.P
14. The diamond grain unsuitable for sawing direction means parallel to: ()
A.{ 100} direction
B.{ 1 10} direction
C {111} direction
Third, multiple choice questions
1. Diamonds and emery (synthetic α-SiC) can be distinguished by the following instruments: ()
A. thermal conductivity meter
B. Infrared reflector
C. conductivity meter
D. ultraviolet fluorescent lamp
E. magnifying glass
2. Compared with diamond, moissanite (SiC) () was synthesized.
A. Different refractive indices
B. Different conductivity
C. there cannot be birefringence.
D. Different ultraviolet absorption
E. the thermal conductivity meter is indistinguishable.
Iv. Fill in the blanks (65438+ 0 points per grid, ***60 points)
The abbreviation of 1. diamond classification standard is 4C, and its Chinese meanings are CARATWEIGHT (), COLOUR (), CUT () and CLARITY ().
2. The colored light in colorless diamonds is caused by light (); The color of opal is caused by light.
3. Refractive index of diamond Under different wavelengths of light, the refractive index of diamond is ().
4. Diamond clarity classification can be divided into LC grade (), VVS grade (), VS grade (), SI grade () and P grade ().
5. The standard magnifying glasses for diamond identification should be (), () and ().
6. Write down three kinds of artificial imitations of diamonds that can best be confused with the real ones: ① (), ② () and ③ ().
7. The "4C" grading standard for diamonds is applicable to polished diamonds with () color system, but not to diamond grading with () color system and () diamonds and () diamonds.
8. The tone of the diamond color grading environment should be (), and the () lamp should be used for grading, with () as the background.
9. According to the genetic mechanism, the color of diamonds can be summarized as A, yellow or blue, because ().
B. Brown and pink are because of (). C. Green is related to ().
10. According to national standards, the external defects that do not affect the classification of diamonds into LC grades are: () and ().
1 1. When determining the clarity grade of a diamond, (), (), () and so on must be considered.
12. At present, the most commonly used diamond substitute on the market is (), and the latest imitation is (). The biggest difference between the latter and diamond is () and the phenomenon of ghosting when magnified.
13. diamond maintenance methods are: (), (), etc.
14. The color classification of diamonds is based on () under the background of diamond lamp and white, and the color grade of diamonds is determined by comparing the color of samples with ().
15.IIb diamonds are often blue, which is caused by the selective absorption of ().
16. A bare diamond pavilion is so shallow that a white ring can be seen from the table. This kind of diamond is called ().
17. The chemical composition of mosangshi is hexagonal SiC (moissanite), usually () color or () color. When it is recognized, it is highly visible and heterogeneous.
18. The four main reasons why diamonds are colored are (), (), () and ().
19. The color of blue diamonds is caused by (), and most natural blue diamonds are of () type.
20. There are two loose diamonds, one of which is easy to observe tiny defects under the magnifying glass of 10 times, which should be classified as () according to the national standard. The other one is easy to observe obvious defects under the magnifying glass of 10 times, and should be rated as () according to the national standard.
2 1. The common forms of diamonds are (), () and ().
22. There are two loose diamonds. Under the magnifying glass of 10 times, the diamond is flawless inside and outside. A diamond has an extra facet in the pavilion, and the crown is invisible. According to national standards, it should be classified as (); The other diamond has a primary crystal plane at the waist, but it does not affect the waist symmetry, and the crown is invisible. According to national standards, it should be designated as ().
23. Synthetic diamonds are often yellow, which is () color and belongs to () type synthetic diamonds.
24. There are () and () methods to quickly distinguish diamonds from imitation diamonds (except synthetic α-SiC).
25. The formula for estimating the weight of a diamond includes waist circumference, height and ().