Through the technology of lab diamond, people can obtain diamonds of high purity and transparency, and the formation process of these diamonds can be controlled and customised as required.
With the continuous development of advanced technology, there is a kind of diamond that is grown in a laboratory. It is called cultured diamond, also known as lab grown diamond, which has the same composition as natural diamonds, and it is impossible to distinguish it with the naked eye. And the purity is higher compared to natural diamonds in the wild, isn't that amazing? So how are diamonds grown?
The laboratory diamond process can be summarised in the following steps:
The first step is to prepare the seeds. To grow diamonds, a natural diamond is used as a seed and placed in an incubator to provide an atomic structure template for the diamond's growth. This seed acts as a guide, allowing the newly created diamonds to grow in the same structural form.
The second step is to create a high-temperature, high-pressure environment. In the incubation silo, the rapid rise in temperature and pressure creates a high-temperature, high-pressure environment over a hundred kilometres deep in the earth, a harsh condition for artificially creating natural diamonds. This environment encourages the carbon atoms in the raw material to rearrange themselves to form the structure of the diamond crystals.
The third step is the addition of carbon-containing nutrients. Graphite or methane, the carbon source, is added inside the culture silo, and under the high-temperature, high-pressure environment and special treatment, the chemical bonds between the carbon atoms in the raw material are broken, and they become free carbon atoms. These free carbon atoms will be attracted to the nearby carbon atom structure, and thus gradually attach themselves to the diamond seed, combine with the carbon atoms of the diamond seed, form a new chemical bond, and the seed will gradually grow.
There are two ways to grow diamonds, one is CVD and the other is HPHT. Diamonds produced by CVD and HPHT have different gemological characteristics. CVD diamonds tend to be more transparent and have fewer small dark inclusions. HPHT synthetic diamonds are closer to the appearance and properties of natural diamonds.
High-Temperature High Pressure (HPHT) method
As early as 1954, scientists had the idea of simulating the environment in which natural diamonds grow in nature and succeeded in creating the first diamonds in the laboratory by applying high pressure and high temperature (HPHT) in a large machine. Three main types of equipment can simulate the environment in which natural diamonds are formed: the Cubic Press, the BARS and the Belt Press. HPHT is the most primitive method of diamond processing and is often used to change the colour of diamonds, such as pink, blue and green.
Today, pure carbon is melted at temperatures of 1300-1600°C and pressures of 870,000 lbf/in2, then cooled and precipitated onto diamond seeds. Due to the structure of the machine, its size and the limitations of the growth process, it is not easy to grow large diamonds by HPHT, so it is mostly used to produce small man-made diamonds. Most diamonds are colourless from D to F, except for a few laboratories that have not yet overcome the technical limitations and have colours below H. The clarity of the diamonds is mostly from VS to SI grades, with the slower the growth rate, the higher the clarity and vice versa.
Chemical Vapour Deposition (CVD)
In 1960, to improve the shortcomings of the HPHT production method, scientists invented chemical vapour deposition (Chemical Vapor Deposition, CVD), this way is to used a diamond as a seed, put it into a vacuum environment and removed all the impurities, the environment heated to 800-1200 ℃, injected into the high temperature of methane and hydrogen, the use of microwave way to release the carbon atoms in the methane. release the carbon atoms in the methane. The colour of CVD-grown diamonds is mainly F~H, and the cleaner the impurities are removed in the vacuum, the better the colour will be, which is what all laboratories are trying to achieve nowadays; the clarity is mostly better than that of HPHT-grown diamonds, and mostly falls in the range of VVS~VS.
The formation of a natural diamond requires the power of nature and a long period. Carbon monomers deep in the rock layers of the earth's crust, after a long time of high temperature and high pressure to form minerals, but also by volcanic eruptions and other lava activities to the shallow surface, were explored, dug out and then carefully polished and designed to appear before consumers. After being packaged by advertisers, diamonds have gradually become a symbol of love in people's minds.
Artificially lab diamonds are 'grown' in a laboratory, using natural diamonds or graphite powder as the raw material, in an artificially simulated diamond growth environment using specific techniques. The process usually takes only a few weeks and the quality of the finished product is as good as, if not better than, that of the natural diamond or graphite powder.
Through the technology of lab diamonds, people can obtain diamonds of high purity and transparency, and the formation process of these diamonds can be controlled and customised as required. The application field of lab diamond is also expanding, not only for jewellery but also for scientific research, industrial fields and so on. At the same time, the production process of lab diamonds is more environmentally sustainable than the mining of natural diamonds.
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