How diamonds are grown in a vacuum?

  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, and the raw materials themselves are not unusual. The reason why it is rare is that the conditions for the formation of diamonds are very harsh.

  Natural diamonds are born in the mantle layer and come to the earth's surface through volcanic activity. Most of the mined natural diamonds belong to industrial-grade diamonds, and there are very few diamonds that can reach jewelry grade. In addition, it is difficult to mine

  With the advancement of science and technology, people began to think: Since the raw materials of diamonds are easy to obtain and the price of diamonds is high, can we produce artificial diamonds? In 1954, General Electric announced that they had produced the first commercially available man-made diamond. So far, lab-grown diamonds have officially entered the industrial and consumer fields.

  Before understanding lab-grown diamonds, we must first understand how natural diamonds are formed.

Natural diamonds are formed at a depth of about 177 to 241 kilometers underground. The pressure at this depth can reach nearly 50,000 atmospheres. The temperature range is from 1100℃~1500℃. These intense geological conditions compressed carbon into its densest form, forming diamonds in magma. Therefore, during the formation of diamonds, temperature, and pressure are important conditions.

  Cultivated diamonds are also called growing diamonds. In layman's terms, small diamonds are used as "seeds" to simulate the growth environment of natural diamonds through technical means, so that the carbon atoms in the "nutrient" gradually attach to the diamond seeds, so that the diamond seeds grow. for larger diamond crystals.

Lab-grown diamonds are comparable to natural diamonds in terms of crystal structure integrity, transparency, refractive index, dispersion, and more. From the data comparison, the optical characteristics, physical characteristics, chemical characteristics, and hardness of cultivated diamonds and natural diamonds are also exactly the same.

How lab-grown diamonds are produced?

  The production technologies for growing diamonds mainly include HPHT (High-Pressure High Temperature) method and CVD (Chemical Vapor Deposition) method, and the cultivation time is about half a month to one month. The high-temperature and high-pressure methods mainly focus on small and medium-sized diamonds, and the growth rate is fast; the CVD method has the advantage of large particles, and the clarity is higher and more controllable.

HPHT

  HPHT mainly uses high-temperature and high-pressure technology to simulate the growth process of natural diamonds, reproduce the reaction of the carbon element layer on the ground, and reconnect the carbon atoms in the carbon powder to form diamond crystals.

•  Put a carbon material, a metal mixture called metal flux and small diamond seeds into the press. The carbon material used is usually graphite;
  
• The press growth chamber is heated to a temperature of 1300°C~1600°C and pressurized to 59,200 atmospheres;
  
• Dissolving the carbon source into the metal flux helps to reduce the temperature required to form diamonds; the carbon source crystallizes slowly around the diamond seed through the molten metal mixture and grows slowly, eventually forming a cultivated diamond rough.
  

CVD

  CVD is the process of uniformly depositing carbon atoms in the gas into natural diamond flakes in a vacuum environment of high temperature and low pressure, and growing to a sufficient thickness to form cultivated diamonds. CVD is suitable for producing rough-grown diamonds over 3.5 carats due to limitations in technology and production costs.

• Evacuate the vacuum chamber and fill the vacuum chamber with mixed gas (including carbon, hydrogen, and oxygen);
  
•  Adding a substrate, usually a seed wafer of diamond seeds, to the vacuum chamber;
  
• Use the microwave, laser, or hot filament to heat the vacuum chamber to a temperature of 800°C~1000°C, the energy from the heat source causes carbon to precipitate out of the gaseous mixture and adhere to the substrate, and the substrate begins to crystallize into the diamond.