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专栏 · 苑博士讲钻石 Column: Dr. Yuan Chat Diamonds In recent years, lab-grown diamonds is a new industry. Countless companies and individuals around the world are entered or considering entering the lab-grown diamond industry. Other countries are directly considering investing in the growth of CVD diamonds. In China, everyone pays attention to both HPHT and CVD. The products obtained in both ways, especially jewelry diamonds, are basically similar, but their industrial uses are quite different. The production efficiency and market of these two models have their own advantages. 1. HPHT growth of diamond is a traditional industry in China. Diamond abrasive products have accounted for more than 95% of global output. If the original production is estimated, China should account for more than 99%. Most of the original products imported from China by other countries, after processing, sorting and then sold for export. Since 2014, China has successfully grown white diamonds for jewelry. In recent years, the size, color and clarity have been gradually improved, and the rough diamonds required for finished diamonds with a finished weight of less than 3 carats have been supplied by quantity. In addition to the existing about ten medium-to-large HPHT growth plants in China, in the growth of jewelry rough, there are also reports that about five or six large-scale new plants are under construction. 2. There are about 100 CVD lab-grown diamond plants in the world, all of which are small and medium-sized, and there are about 20 to 30 in China. Everyone is improving the growth process and machine specifications. The structure of the CVD reaction chamber mainly includes Japanese SEKI clamshell type , SEKI and French straight cylinder type on the market. The domestically produced type is mainly straight cylinder type. As shown below:   ▲ L:Clamshell type resonant cavity CVD reaction chamber R:Straight barrel type resonant cavity CVD reaction chamber The advantages and disadvantages of the HPHT and CVD modes are as follows:  The existing technology of HPHT is the seed temperature differential method, which is a mature technology and there is not much room for improvement. If you want to expand， the press can be expanded to a cylinder diameter of 1000mm (with a sleeve). There are also spontaneous nucleation methods and relay growth methods that may improve the growth effect. There is still a lot of room for improvement in CVD growth technology, such as expanding the growth on size of seed plates, Improve machine structure, material, to reduce the generation of gray and black in color, changing the machine to a large size, as improving the 2 inches tray to 4-6 inches tray. Author  Joe Chih-Chung Yuan, Ph.D. from Sun yat-sen university, Director of Henan Godiam New Material Technology Co., Ltd. Engaged in diamond cutting , identification, researching teaching and growing for more than 44 years. Currently engaged in diamond jewellery cutting, high temperature high pressure(HPHT), chemical vapor deposition (CVD) single crystal, polycrystalline diamonds growing, application researching and production. Established laboratories and diamond cutting and growing factories in New York, Taipei, and Zhengzhou. - Obtained the GIA Graduated Gemologist G.G. — We observe, We share 钻石观察 Contact: diamond-spectator  |
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