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 the depth of 150-200km) and 1 100- 1500 degrees Celsius. 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.

The growth environment of crystals is mostly underground and caves, which requires rich underground water sources, and groundwater mostly contains saturated silicon dioxide. At the same time, the pressure inside it needs to be about two to three times that of atmospheric pressure, and the temperature needs to be between 550 and 600℃. If given a proper time, the crystal will crystallize into hexagonal columnar crystals according to the natural law of hexagonal crystal system.

Usually, in the ideal environment controlled by human beings, that is, when the physical and chemical conditions meet the above conditions, the growth rate of crystals is about 0.8 mm per day. This is also the standard production speed of many intraocular lenses in laboratories and factories. The crystal thus cultivated is the so-called "synthetic Shi Ying", which is usually cut into chips and used in electronics, computer and communication industries. Some people call it "breeding Shi Ying". Although they use different words, they actually mean the same thing. Generally, the thickness of industrial intraocular lens is about 3 cm, that is, 30mm, and it takes about 40 days to grow. It generally takes about180 days for jewelry industry to grind a crystal ball with a size above 10 cm (100mm). However, this speed is only possible in the most ideal environment controlled by human beings. In nature, the situation is not so optimistic because of raw materials, water quality, temperature, pressure and other conditions. Are constantly changing, it is difficult to achieve the ideal situation. It usually takes tens of thousands or millions of times to achieve the same growth. This is the reason why the "geological age" movement takes "million years" as the calculation base, and it is also the precious place of "crystal rock".

When a normal crystal is growing, people often find that the growth line is parallel to the cylindrical tip line. Because of the small growth space in underground and caves, especially in the event of earthquakes or crustal changes, they are even easily squeezed by other minerals, and different "crystal planes" often appear. Also, when crystals are still in liquid state, they are often wrapped by other minerals and marls and grow together, such as rutile (which will become crystals later), volcanic marls (which will become phantom crystals later) and so on. These are "part of nature", please don't treat them as "flaws".

The natural purity of gold is not high, and it is a metal mineral.

These are all based on other people's data. Thank you. .