China's superhard materials industry has undergone more than sixty years of development, starting from extremely difficult conditions, successfully developing China's first batch of diamonds in 1963, and has now become a world-class manufacturing powerhouse with a complete range of categories, superior quality, and abundant output. It not only fully meets domestic market demand but also provides high-quality products to most countries worldwide, contributing to global economic and technological development.
The evolution of China's superhard materials industry is inseparable from the development of domestically produced HPHT Hydraulic Cubic Presss. The HPHT Hydraulic Cubic Pressis considered the sole foundation for static high-temperature and high-pressure synthesis, and its development has led to the growth of the artificial diamond industry in China and globally.
The important milestones in the development of China's HPHT Hydraulic Cubic Presstechnology are as follows:
 Early Exploration and Establishment of Dominance:
    In the early stages of research and development for diamonds and other superhard materials, China explored various types of synthesis equipment, including two-sided, four-sided, and HPHT Hydraulic Cubic Presss.
    In the early 1970s, the four-sided press was eliminated first. The competition between two-sided and HPHT Hydraulic Cubic Presss continued until the early 1990s, when the HPHT Hydraulic Cubic Presswith Chinese characteristics ultimately emerged as the mainstream.
 Development and Miniaturization Breakthrough:
     Starting in 1965, China developed the first generation of dedicated HPHT Hydraulic Cubic Presss with a Φ230mm cylinder diameter. Its main features included a cylinder-beam structure and hinge connections, with pistons moving along three axes to apply pressure to a single center.
     In the early 1970s, the synthesis chamber was only Φ10mm, but researchers realized that expanding the chamber could not only increase yield but also improve quality, thus beginning to explore the possibility of larger chambers.
    Subsequently, different chamber sizes appeared, such as Φ12mm, Φ(1516)mm, and Φ(1820)mm. However, the Φ18mm chamber was widely promoted domestically, increasing diamond strength from 18N to 100-110N.
 First "Large Press" Breakthrough:
     Around 1976, the "small press" limitation was first overcome, achieving "large presses" with Φ(280~320)mm. This type of press initially reached a synthesis chamber of Φ23mm, later stabilizing at Φ(25~28)mm. At this point, a single run could yield 10-15 carats or more, with diamond strength reaching 150-180N.
 Transitional Stage of Press Enlargement:
     Starting in 1990, various presses with Φ(360，400，420，450，480)mm were developed. During this stage, the concept of press enlargement gradually took shape. The anvil diameter reached Φ(90103)mm, and the synthesis chamber gradually reached around Φ(3040)mm. Single-run yields reached 35-60 carats, with TI > 70 and TTI > 50.
  First Stage of Press Enlargement:
     Φ(500560600~650)mm presses began to use PLC plus human-machine interface control systems, improving system stability, ease of operation, and reliability, and enabling automatic process tracking.
     The main diamond grit sizes were concentrated at 30/45 mesh. After extended synthesis, 3-7mm large single crystals could be synthesized, with TTI (Thermal Impact Toughness) values of approximately 75%-90% and TI (Cold Impact Toughness) values above 85%-93%. The yield of high-quality products reached around 50%, and anvil consumption dropped to below 0.5-1 kg/10,000 carats. At this point, the overall level of China's superhard materials was close to internationally advanced levels.
 Second Stage of Press Enlargement:
    Φ(700750800)mm presses adopted programmable PLC as the main control system, a computer-equipped system that could verify design tracking programs and perform "memory (storage)," enabling artificial intelligence design to improve diamond product yield and quality.
    For a Φ54mm chamber, the stable single-run yield of synthesized diamonds reached 220-250 carats/block, with a maximum of over 300-320 carats/block. After extended synthesis, 3-7-10mm large single crystals could be synthesized, with TTI values of approximately 75%-90% and TI values above 85%-93%. The yield of high-quality products reached over 50%, and anvil consumption was below 0.3 kg/10,000 carats. At this point, the overall level of China's superhard materials had reached internationally advanced levels.
 Extended Stage of Press Enlargement:
    Starting in 2012, Φ(8501000≥1000)mm presses were developed. The Φ850mm cylinder diameter press has matured, with over 1000 units produced nationwide (including export presses).
    The control system for new large presses still uses programmable PLC, but with higher demands for control accuracy and stability due to increasing costs of raw and auxiliary materials.
    These presses are mainly used for large single crystal particles (10≥20mm), large composite sheets (Φ(627075)mm, even ≥8090mm), and experimental research and application of static ultra-high pressure (≥30~50万 atmospheres).
  Reasons for the Appearance of Many Different Cylinder Diameter Presses:
    The most significant reason is that the manufacturing difficulty of cemented carbide anvils (press anvils) increases with diameter, undergoing a research-development-stabilization process. From initially producing only Φ70mm anvils, China gradually developed Φ(7580)mm, Φ(90105)mm, Φ(122160)mm, Φ(168200)mm, and ≥Φ200mm anvils. Presses could only be made larger when anvil performance was up to standard.
    The enlargement of presses is a gradual and reasonable process.
    The excessive number of early diamond production enterprises in China, with many lacking strong technical support, led to market consolidation. Today, there are only about a dozen truly powerful and distinctive diamond production enterprises.
  Current Status and New Developments of Presses:
    Currently, China's six-sided dedicated diamond presses continue to maintain the trend of enlargement.
    The total number of presses with cylinder diameters above Φ500mm has reached over 7000 units.
    Φ(500~560mm) cylinder diameter presses have become small presses, accounting for about 15% of the total.
    Φ(600~750mm) cylinder diameter presses have become the main presses, accounting for 40%-45% of the total.
    There are over 20 presses with cylinder diameters exceeding Φ850mm, and they are operating stably.
    The manufacturing process for "non-cylinder presses" has begun to mature, with over a thousand units produced, accounting for nearly 20% of the total. Non-cylinder presses have a simple structure, require less maintenance, are easy to maintain, and have lower costs. Experimental production pressures can exceed 105MPa, comparable to cylinder presses, and have successfully synthesized various chamber sizes.

China's HPHT Hydraulic Cubic Presstechnology is simple but offers strong advantages in comprehensive control of temperature, synthesis chamber pressure, and environmental conditions. It can provide greater synthesis pressure to increase single-run output, thereby improving production efficiency, reducing costs, and yielding good economic benefits. With continuous enlargement and precision, China's HPHT Hydraulic Cubic Presstechnology shows broad application prospects for high-temperature and high-pressure synthesis of large single crystals, PDC, NPD, and other materials.