Fig. shows an analogous experiment for a diamond NP with initial mass of 138.4 MDa (a large aggregate of nano-diamonds). To minimize structural evolution prior to the initial oxidation, the 1900 K sublimation step was omitted, and the NP was never heated above the 1300 K oxidation temperature, thus this experiment should be directly comparable to the long-term oxidation experiment in Fig. . As in many of the diamond NP experiments, as TNP was initially ramped from 1150 to 1300 K in argon, there was very fast loss of ~192 kDa of mass, attributed to desorption of adsorbates, then Rbase stabilized at ~0.053 Da/sec/nm 2 . When O2 was added, the mass loss accelerated and was nearly constant over the 10 minute initial oxidation period, resulting in an initial EEO2 (10 -3 Da/O2 collision) in the same range as those for other carbon NPs under similar conditions. Note, however, that Rbase measured just after this oxidation period was much slower than Rbase just before, indicating that significant evolution occurred in just ~10 minutes of oxidative etching. The NP was then annealed in argon at 1300 K for ~22 hours, during which it lost ~1.1 MDa (~0.8% of Minitial), and clearly Rbase continued to slow throughout the annealing period. When the annealed diamond NP was exposed to O2, EEO2 was found to be ~3.2 x 10 -4 Da/O2 collision, i.e., the long annealing period resulted in decreased reactivity, but only by a factor of ~3. For comparison, in Fig. , the final EEO2 was only ~2.5 x 10 -5 , even though the oxidation period was only 10.8 hours long. Both the modest effect of long-term annealing in argon and the large decrease in Rbase after the initial oxidation period, suggest that oxidizing conditions also promote evolution of diamond NPs toward O2 inertness, although the results in Figs. and show that annealing in the 1900 K range also renders diamond NPs O2 inert (unlike the graphite, graphene, carbon black, and graphene oxide NPs).