Jade is also the beauty of stone. But it also has bright colors, hard and delicate texture, and beautiful luster after polishing.
From the current gemmology, the concept of gem can be divided into broad sense and narrow sense.
In a broad sense, gemstones are indistinguishable from jade. Generally, gemstones refer to minerals or rocks with magnificent colors, hardness, durability and rarity, which can be polished and carved into jewelry and handicrafts, including natural and synthetic materials and some organic materials.
In a narrow sense, there are precious stones and jade. Gem refers to a single mineral crystal with magnificent color, crystal clear, hard, durable and rare, which can be polished into gem jewelry, including natural and synthetic, such as diamonds and sapphires. Jade refers to mineral aggregates or rocks with magnificent colors, hardness, durability and rarity, which can be polished and carved into jewelry and handicrafts, such as jadeite, nephrite, dushan jade and jade, both natural and synthetic.
Jade also has a narrow sense and a broad sense. In a narrow sense, it only refers to jadeite (represented by Burmese jadeite) and nephrite (represented by Hetian jade). Broadly speaking, it includes many kinds of minerals and rocks used for handicraft carving. As for colored stone, it refers to the low-grade arts and crafts stone with beautiful and delicate color and texture, low hardness and weak luster, but it can meet the requirements of processing technology. Some scholars advocate that colored stones should be included in the broad sense of jade, or that colored stones should be used as synonyms for jade for the time being.
Brief introduction of diamonds
Chinese name: diamond
English name: Diamond
Mohs hardness: 10
Chemical composition: 99.98% carbon.
Physical properties: It has the highest hardness among natural minerals, and its brittleness is also quite high, and it will still break when it hits hard. From the ancient Greek agonist, which means hard and inviolable substance, it is recognized as the king of gems. Diamonds In other words, diamond is actually a kind of carbon crystal with quite high density.
Common shapes: round, oval, olive pointed, heart-shaped, pear-shaped, square, triangle, emerald-shaped. A round drill is the most common shape.
Refractive index: 2.4 17
Dispersion value: 0.044 (high)
Total internal reflection: critical angle: 24.5.
Main producing areas: The main producing areas of diamonds are Australia, Botswana, Canada, Zimbabwe, Namibia, South Africa, Brazil and Siberia; At present, 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.
The quality unit card, or translated carat or carat, is the quality unit 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.
Chemical composition The chemical composition of a diamond is carbon, which is the only single element in a gem and belongs to an 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. The crystal forms are mostly octahedron, rhombic dodecahedron, tetrahedron and their aggregates. Pure diamond is 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 by thermal conductivity meter, the response is the most sensitive. The hardness is 10, which is the hardest mineral known at present. The absolute hardness is 1000 times that of the time, and 150 times that of corundum. It is afraid of heavy blows, and it will be broken by cleavage after heavy blows. A set of cleavage is completed. The density is 3.52g/cm3. Diamonds are luminous, and after being irradiated by sunlight, they can emit light blue phosphorescence at night. X-ray irradiation emits 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 precious stones 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 and high density of 5.8 g/cm3, which has obvious sense of gravity. Yttrium aluminum garnet has a soft dispersity, so it is difficult to distinguish it from diamonds with naked eyes.
Formation principle Some people say that diamonds are diamonds, but this statement is completely wrong (their difference is equivalent to the relationship between wood and furniture). Diamonds are just products of diamond processing. Modern science, technology and means provide new ideas and methods for exploring the formation of diamond. 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). In order to understand the origin of diamonds, first look at the original rocks containing diamonds.
Since the discovery of diamonds in India, we have been hearing stories about people finding 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 downstream with the water flow, and the heavier diamonds are buried in the gravel. What is the original stone of a diamond? 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. What is 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.
Through the study of diamonds and their primary inclusion minerals from different mines in the world, scientists found 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 currently mined were mainly formed in two periods: 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.
Rare diamonds are mainly produced in two kinds of rocks, one is peridotite and the other is eclogite, but only the former has economic significance. So far, there are two kinds of peridotite containing diamond: kimberlite (named after a place name in South Africa-kimberlite) and K-Mg lamprophyre. Both kinds of rocks are produced by volcanic eruption. Rocks formed in the deep part of the earth are brought to the surface or the shallow part of the earth by volcanic activity. This magma is mostly produced in the form of rock tubes, so it is commonly called "tube ore" (primary ore). Kimberlite or kimberlite containing diamond is exposed to the surface and weathered and broken by external forces such as wind and rain. Under the scouring of water, the broken protoliths and diamonds are taken to the riverbed and even the coastal zone for reproduction, forming alluvial sand deposits (or secondary deposits).
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