According to Mohs hardness scale) * * *, the scale is 10, as follows:
Grade 1: talc
Grade 2: gypsum
Grade 3: calcite
Grade 4: fluorite
Grade 5: apatite
Sixth grade: orthoclase
Seventh grade: timely
Grade 8: topaz
Ninth grade: Yu Gang
Grade 10: diamonds
Expand knowledge about diamonds;
Overview:
Diamond refers to polished diamond, which is a natural mineral and the original stone of diamond. Simply put, diamond is a simple crystal composed of carbon element formed under high pressure and high temperature conditions in the deep part of the earth. Diamonds are beautiful and rare. They are symbols of love and loyalty, representing eternal love.
On May 17 and 16, Sotheby's held a spring jewelry auction in Geneva, Switzerland. A pair of colored pear-shaped diamond earrings set a new record in the auction history with a total price of about 57.4 million US dollars (about 395 million yuan). This pair of pear-shaped earrings is made in South Africa. Except for the different colors, the appearance is almost the same, weighing about 16 carats respectively. Among them, the dark pink diamond was named "Artemis", which earned US$ 6,543.8+0.55 million (RMB 654.38+0.067 million), and the other diamond was named "Apollo" because of its rare color, which was more than twice as expensive as the pink diamond.
Formation principle:
Diamonds are the products of diamond processing. Diamonds are the hardest and simplest gems in the world. It is a cubic natural crystal composed of carbon. Its composition is basically the same as our common coal, pencil lead and sugar. Under high temperature and pressure, carbon element crystallizes to form graphite (black), while under high temperature, extremely high pressure and reducing environment (usually anoxic environment), it crystallizes to become precious diamond (colorless).
Since the discovery of diamonds in India, some people have found diamonds on rivers and beaches. This is because the original rock containing diamonds located in the upper reaches of the river is weathered and broken, and the diamonds are taken to the downstream zone with the water flow, and the heavier diamonds are buried in the gravel.
1870, diamonds were dug up in the loess of a farm in South Africa. After that, the excavation of diamonds moved from the river bed to the loess. Below the loess is a hard dark blue rock, which is the original stone of diamonds-kimberlite. Kimberlite is an alkaline ultrabasic volcanic rock, which is formed in the deep part of the earth and contains a lot of volatile components such as carbonic acid gas. This kind of rocks often contain peridotite and eclogite fragments from the deep earth, and the main mineral components are olivine, phlogopite, carbonate, pyroxene and garnet. The study shows that kimberlite magma was formed in the deep part of the earth below 150 km. Because this rock was first discovered in Kimberly, South Africa, it was named after this place name.
Another kind of original rock containing diamonds is called K-Mg lamprophyre, which is an overbased magnesian volcanic rock. It is mainly formed by leucite and volcanic glass, and may contain minerals such as pyroxene and olivine. Its typical origin is argyle, Western Australia.
The study of diamonds and their primary inclusion minerals from different mines in the world shows that the formation conditions of diamonds are generally 4.5-6.0Gpa (equivalent to 150-200km depth) and1100-1500℃. Although diamonds can be formed in various periods/stages of the earth's history in theory, most of the mines mined were mainly formed 3.3 billion years ago and12-1700 million years ago. For example, some diamonds in South Africa are about 4.5 billion years old, indicating that these diamonds began to crystallize in the deep part of the earth shortly after its birth. Diamonds are the oldest gems in the world. The formation of diamonds needs a long historical process, which can be confirmed by the fact that diamonds are mainly produced in the ancient and stable mainland areas of the earth. In addition, the impact of extraterrestrial stars on the earth can produce instantaneous high temperature and high pressure, and can also form diamonds. For example, the report of the former Soviet Academy of Sciences 1988 found diamonds in meteorites, but the diamonds formed by this action have no economic value.
Division of origin:
Diamonds are produced all over the world, and more than 30 countries have diamond resources with an annual output of about 1 100 million carats. The five countries with the highest output are Australia, Zaire, Botswana, Russia and South Africa. The diamond production of these five countries accounts for about 90% of the world's diamond production. Other diamond producing countries include Congo (DRC), Brazil, Guyana, Venezuela, Angola, Central Africa, Ghana, Guinea, C? te d 'Ivoire, Liberia, Namibia, Sierra Leone, Tanzania, Zimbabwe, Indonesia, India, China and Canada.
The main diamond cutting and grinding centers in the world are Antwerp, Tel Aviv, new york, Mumbai, Thailand and Bangkok. Antwerp has the reputation of "the diamond capital of the world", where about half of the world's diamond transactions are completed. "Antwerp Cutting" is synonymous with perfect cut.
Main reserves:
General situation of world diamond reserves and production;
The proven natural diamond reserves are about 2.5 billion carats, including 650 million carats in Australia and 550 million carats in Zaire. According to the mining level, the existing diamond reserves can only be mined for 25 years, but with the improvement of prospecting technology, new mining areas are discovered every year, and the diamond reserves in Canada have increased greatly in recent years.
Since the diamond mining, * * * has mined about 350 tons of diamonds, that is, 65.438+75 billion carats. The annual diamond mining volume in the world is 90-65.438+0 billion carats, of which the gem grade accounts for 654.38+07%-20%. The value of 20% gem-grade diamonds is five times that of 80% industrial diamonds.
Simple identification:
Simple identification method of diamonds: you need a magnifying glass of 10-20 times as an aid to make a few simple observations.
(1) Observe the waist of the diamond. If the waist is frosted, this method is most suitable. Because diamonds are harder than any imitations, there will be no fine lines like imitations, and the waist of diamonds has a granular appearance.
(2) Diamonds are harder than imitations, and the faceted edges of imitations are often duller than diamonds, and the faceted edges of diamonds must be sharp.
(3) Because diamonds are harder than imitations, the facets of imitations are often worn away.
(4) If a diamond has a natural surface, there is a chance to find a unique "triangular growth line" on the natural surface.
(5) If the diamond is broken, the appearance is usually stepped, while the imitation will be completely bent or shell-shaped.