How can I generate 250 GPa to create metallic hydrogen?

In the preparation of metallic hydrogen, how does one conjure up such immense pressures?


I mean, I read that something like diamond anvils were used to contain the hydrogen, but now, in accordance with Newton's 3rd law, shouldn't the diamond also face the same extreme forces? 


I mean a 10 on the Mohs scale is very high, but how does that suffice to withstand the immense force applied back by the compressed gas?




According to [The Compressive Strength of a Perfect Diamond](http://faculty.csuci.edu/david.nelson/Compressive%20Stregth%20of%20Diamond.pdf) 410-480 GPa is possible. So, yes, the diamond experiences the applied pressure, but it is strong enough to sustain it. 


For more recent work, see [Implementation of micro-ball nanodiamond anvils for high-pressure studies above 6 Mbar](http://www.nature.com/articles/ncomms2160)


 3