(1) The CVD technology is advanced, the purity is high but the color is poor, so it is used in the high-tech field:
- Large particle size: At present, all bare diamonds above 1.5ct are produced by CVD technology;
- Color difference: In order to increase production capacity, manufacturers will add nitrogen to accelerate the growth of cultivated diamonds, which can increase production capacity. However, this will turn the diamond yellow, requiring a color change. The certificate indicates whether it has been altered;
- Advanced technology: Machines are hard to buy, high-end CVD equipment may cost more than 3 million yuan, and the quality of the diamonds grown will be very good. For example, domestic CVD can achieve DEF color, and the definition can reach VVS/VS. Most CVD companies can only achieve G-J color, which needs to be changed; because nitrogen is not added in the production process, the growth rate is slower than HPHT, and the productivity is not high enough;
- Industrial use: CVD will be used in a wider range of industrial fields than HPHT, and more in high-tech fields, such as the semiconductor industry, heat dissipation, aerospace, etc. Because the production cost has not come down, the industrial demand cannot be mass-produced.
(2) The HPHT method has good color but small particles and low transparency, and is used in low-end industrial fields:
- Small particles: In recent years, the HPHT technology has been continuously breaking through, and colorless and transparent crystals with large particles can be slowly produced in batches. The largest loose diamond produced by energy is 1.5ct, or is it smaller than the CVD method?
- Low transparency: The metal catalyst used in the production process is liquid. After crystallization, this part of the metal catalyst may solidify into diamond crystals, and some small diamonds may be attracted by magnets.
- Industrial application: HPHT has been used in China for a long time, mainly for abrasive tools and small-grain diamond abrasive grains.
(3) The two will not form a technical subversion:
- From the point of view of industrial drill bits, HPHT and CVD are differentiated and have different dimensions of competition: HPHT industrial drill bits are in very high demand. Global demand for industrial-grade diamonds is around 20 billion carats, equivalent to around 8,000 HPHT machines. At present, the domestic diamonds are about 1W, including 7,000 industrial diamonds and 3,000 jewelry-grade diamonds, so there is a gap of 1,000 industrial diamonds.
- From the perspective of jewelry-grade diamonds, HPHT is suitable for diamonds under 1ct, and CVD is suitable for large-carat diamonds: the production cost of HPHT is much lower than that of CVD, and it has advantages in the production of small carats. Can do a lot of fashion jewelry, very large, such as pendants, earrings, rings, domestic demand for these kinds of large; CVD is suitable for wedding diamonds. From the economic point of view, it is generally not possible to cut large diamonds into small ones. If a blank can be cut with 2ct, cutting two pieces of 1ct is a loss, and cutting four pieces of 50 points is a loss.