# Is it possible to make very large diamonds using a pressure vessel at several GigaPascal pressure?

Nanocrystalline diamonds can be synthesized by direct conversion of graphite or carbon black mixed with low amount of boron (0.1%-10%) at 8-10 GPa, according to US patent No.20120255236.

If some scientists decided to make very large monolithic diamonds (tens of cm size) to make for example large diamond anvil cells with a centimeter sample size, would it be practical to use large pressure vessels with very thick steel walls to reach such very high hydrostatic pressures for such a large volume?

How to calculate the required material thickness to withstand such high pressures?

• See, how well looks your question after my edit. – peterh Jun 27 '17 at 5:52
• Just takes lots of money and massive containers. But why bother when there are simpler (chemical) methods? – Carl Witthoft Jun 27 '17 at 13:35
• Carl Witthoft , what is the simpler method to make 10 cm size diamond ? I didn’t hear about something similar – anameen Jun 28 '17 at 5:19

There are two main methods of making synthetic diamonds. HPHT (High pressure, high temperature), which uses something like a Diamond Anvil Cell to achieve pressures in the Gigapascal range and temperatures over 1400 $^o$C. The largest diamonds produced this way seem to be in the 1-2 cm range but it is difficult to get reliable information on this.