Fig. shows that evolution of graphite NPs toward inertness is greatly accelerated under O2 etching conditions, compared to inert conditions at the same TNP. The origin of this effect is not clear, however, for TNP in the 1500 K range, sublimation is negligible and because TNP is only at ~30% of the graphite melting point (4800 K at high pressures) annealing is presumably also slow. Under etching conditions, the rate at which material is removed and the rate at which new under-coordinated sites are exposed by loss of carbon atoms, are relatively fast, with most of the action occurring at the prismatic faces. Thus, etching tends to re-shape the prismatic edges, creating under-coordinated sites that potentially can link together to start the process of creating arched edges. Because etching occurs primarily at under-coordinated sites, once arched structures are formed, they should be less reactive than the surrounding prismatic surface. The waves of etching, separated by periods of low reactivity imply that the graphite NPs can become capped with a fully-coordinated and nearly inert surface layer, but that this layer can be disrupted and etched away, exposing the underlying highly reactive prismatic faces.