  We show that the cross section for inclusive charm production exhibits
geometric scaling in a large range of photon virtualities. In the HERA
kinematic domain the saturation momentum $Q_{sat}^2(x)$ stays below the hard
scale $\mu_c^2=4m_c^2$, implying charm production probing mostly the color
transparency regime and unitarization effects being almost negligible. We
derive our results considering two saturation models which are able to describe
the DESY ep collider HERA data for the proton structure function at small
values of the Bjorken variable $x$. A striking feature is the scaling on
$\tau=Q_2^2/Q_{sat}^2(x)$ above saturation limit, corroborating recent
theoretical studies.
