  Artificial diamond is created by exposing graphite to pressures on the order
of 10\,GPa and temperatures of about 2000\,K. Here, we provide evidence that
the pressure exerted by the tip of an atomic force microscope onto graphene
over the carbon buffer layer of silicon carbide can lead to a temporary
transition of graphite to diamond on the atomic scale. We perform atomic force
microscopy with CO terminated tips and copper oxide (CuOx) tips to image
graphene and to induce the structural transition. For a local transition, DFT
predicts that a repulsive barrier of $\approx13$\,nN, followed by a force
reduction by $\approx4$\,nN is overcome when inducing the graphite-diamond
transition. Experimental evidence for this transition is provided by the
observation of third harmonics in the cantilever oscillation for relative
flexible CO terminated tips and a kink in the force versus distance curve for
rigid CuOx tips. The experimental observation of the third harmonic with a
magnitude of about 200\,fm fits to a force with an amplitude of $\pm 3$\,nN.
The large repulsive overall force of $\approx 10$\,nN is only compatible with
the experiment if one assumes that the repulsive force acting on the tip when
inducing the transition is compensated by an increased van-der-Waals attraction
of the tip due to form fitting of tip and sample by local indentation. The
transition changes flat sp$^2$ bonds to corrugated sp$^3$ bonds, resulting in a
different height of the two basis atoms in the elementary cell of graphene.
Both tip types show a strong asysmmetry between the two basis atoms of the
lattice when using large repulsive tip forces that induce the transition.
Experimental data of tunneling current, frequency shift and dissipation are
consistent with the proposed transition. The experiment also shows that atomic
force microscopy allows to perform high pressure physics on the atomic scale.
