When it comes to diamonds, we often associate them with being expensive and hard. As we all know, the main component of diamonds is carbon, the raw material itself is not unusual. They are rare because the conditions under which diamonds are made are so demanding.
Natural diamonds are born in the mantle layer and come to the Earth’s surface with volcanic activity. Most of the natural diamonds after mining belong to industrial grade, and few diamonds can reach jewelry grade. Moreover, it is difficult to mine, so in the past, diamonds were monopolized by the royal family and aristocrats for a long time.
As science and technology improved, people began to wonder: since the raw material for diamonds was so easy to obtain and the price of diamonds was so high, could we produce synthetic diamonds? In 1954, the General Electric Company announced that it had produced the first synthetic diamond for commercial use. At this point, the cultivation of diamonds formally entered the industrial and consumption field.
How to grow diamonds
Before we can understand growing diamonds, we need to understand how natural diamonds are formed.
Natural diamonds are formed about 177 to 241 kilometers deep underground. The pressure at this depth can reach nearly 50,000 atmospheres. The temperature ranges from 1100℃ to 1500℃. These intense geological conditions compress carbon into its densest form, forming diamonds in magma. So temperature and pressure are important conditions in the formation of diamonds.
The cultivation of diamonds, also known as growing diamonds, is to use small diamonds as “seeds”, through technical means to simulate the growth environment of natural diamonds, so that the carbon atoms in the “nutrients” gradually attached to the diamond seeds, so that the diamond seeds grow into larger diamond crystals.
Cultivated diamonds are comparable to natural diamonds in terms of crystal structure integrity, transparency, refractive index and dispersion. lab grown diamonds manufacturer. From the comparison of the data, the optical properties, physical properties, chemical properties and hardness of cultivated diamonds and natural diamonds are exactly the same.
The way diamonds are produced
The main production technologies for diamond cultivation include HPHT (High Pressure High Temperature) and CVD (Chemical Vapor Deposition), and the cultivation time is about half to one month. The high temperature and high pressure method mainly consists of small and medium-sized diamond particles, and the growth rate is fast. CVD method has the advantage of large particles, higher clarity and more controllable.
High Temperature and High-pressure method (HPHT)
HPHT mainly simulates the growth process of natural diamonds by using high temperature and high pressure technology to reproduce the reaction of the carbon layer on the ground, so that the carbon atoms in the toner can rejoin to form diamond crystals.
A metal mixture containing a carbon material, called a metal flux, and small diamond seeds are placed in a press. The carbon material used is usually graphite.
Heating press growth chamber to 1300℃~1600℃ temperature, and pressure to 59,200 atmospheres;
Dissolving carbon sources into metal fluxes helps reduce the temperature needed to form diamonds. The carbon source grows slowly by crystallizing a mixture of molten metals around the diamond seed, eventually forming a cultivated diamond blank.
Chemical Vapor Deposition (CVD)
CVD is a high temperature and low pressure vacuum environment, so that the carbon atoms in the gas uniformly deposited into natural diamond flakes, grow thick enough to form cultivated diamonds. CVD is suitable for producing cultivated diamond rough over 3.5 carats due to process and production cost constraints.
Vacuum the vacuum chamber and fill it with a mixture of gases (including carbon, hydrogen and oxygen).
The substrate, usually a diamond seed sheet, is added to the vacuum chamber;
Microwave, laser or hot filament is used to heat the vacuum chamber to a temperature of 800℃~1000℃. The energy from the heat source precipitates carbon from the gaseous mixture and adheres to the substrate, which begins to crystallize into diamond.
Cultivate a global diamond industry chain
The upstream industry of diamond cultivation mainly includes: cultivation of diamond raw materials, cultivation of machinery and equipment, and cultivation of diamond production suppliers. According to statistics, 40% of the world’s cultivated diamond raw stone from China, manufacturers mainly concentrated in Henan.
The midstream industry focuses on the cutting, polishing and polishing of rough diamonds and the finished trade of diamond cultivation. 95% of the diamond processing industry is concentrated in India, where labor is cheap and intensive. Downstream industries include retail and jewelry brand sales, with the main consumer market concentrated in the United States.
According to Bain & Company data, in 2020, 90% of the cultivated diamonds produced by high temperature and high pressure technology in the world will come from China, and Russia will account for 6%. China almost monopolizes the global production capacity of HPHT diamonds. The diamond production capacity of CVD is evenly distributed, with India, the United States, Singapore, Europe and the Middle East accounting for 37%, 25%, 25% and 13% respectively.
In 2018, the global production of cultivated diamonds was 1.44 million carats, with a penetration rate of only 1%. Due to the impact of COVID-19 and the shortage of natural diamond raw materials, the global total diamond production decreased. In order to meet the demand of diamond consumption in the market, the production of cultivated diamonds increased, and the permeability increased steadily. The production of cultivated diamonds in 2019 and 2020 will be 6 million carats and 7 million carats, respectively, with a penetration rate of 4.1% and 5.9%.
In addition to jewelry consumption, cultivated diamonds are also used in semiconductor materials. CVD industrial diamond can be used for high precision functional materials. As the world rushes to develop semiconductor diamonds, Japan has successfully developed ultra-pure 2-inch diamond wafers that can store as much as 1 billion Blu-ray discs.
CVD diamond can be used in semiconductor chips, electronic devices heat dissipation, such as diamond wafer splicing way to make CVD large area single crystal wafer, as LED, semiconductor chip substrate, can completely solve the heat dissipation problem. In the future, industrial semiconductors are where the largest use of diamonds will be, with demand expected to be a hundredfold that of jewelry diamonds.