Fig. shows the results for a 17.3 MDa (~28.9 nm) graphite NP. As in Figs. , and S11, TNP was briefly set to 1900 K to clean the surface, and allow measurement of Rsublimation, which was ~0.59 Da/sec/nm 2 -comparable to the 1900 K Rsublimation values for the graphite NPs in Figs. , and S11. TNP was then dropped to 1300 K for Q-stepping, and then held at 1500 K for the rest of the experiment. The initial 1500 K Rbase was also similar to values for the other graphitic NPs, and when 4.3 x 10 -5 Torr of O2 was added, EEO2 averaged over the 10 minute initial oxidation period was ~2.5 x 10 -3 Da/O2 collision, also in the range typical of black carbon NPs. The NP was then held in argon for more than 22 hours (note break and change in time axis), resulting in just ~0.55 MDa (~3%) mass loss, corresponding to average Rbase ≈ 3 x 10 -3 Da/sec/nm 2 . After the long annealing period, O2 was re-introduced for a second oxidation period, and while EEO2 fluctuated, the average EEO2 was ~3.6 x 10 -3 Da/O2 collision, i.e., 30% higher compared to the initial EEO2 value. Clearly, heating in argon did not result in anything close to the three to four orders-of-magnitude decreases in EEO2 observed for graphite, graphene, 5 carbon black, and graphene oxide NPs held under oxidizing conditions. The difference is clearly not Figure . A). A graphite NP is oxidized at 1500 K, annealed for >22 hours, and oxidized again. B). A similar experiment on a diamond NP without pre-heating to 1900 K. C). The same experiment in frame A, but for a nano-onion NP. simply a result of the relatively small sublimation mass loss, because carbon black NPs become inert for similar mass losses.