A Physics Web article on aggregated diamond nanorods [hat tip: Instapundit] contains the following contradiction:
The group created the ADNRs by compressing the carbon-60 molecules to 20 GPa, which is nearly 200 times atmospheric pressure, while simultaneously heating to 2500 Kelvin.Of course, 200 atmospheres is only 20MPa (roughly the pressure a mile deep in the ocean) -- 20 GPa (giga Pascals, i.e., billions kg / m s^2) is 200,000 atmospheres. For comparison, the pressure at the center of the earth is estimated at around 375 GPa.
I have no idea how one goes about creating pressure like that in a lab. Google to the rescue!