The diamond NP in Fig. was ~50 times more reactive when initially exposed to O2 at 1200 K, and remained ~10 times more reactive even after TNP had been ramped to 1400 K. The diamond NP in Fig. was also substantially (~20x) more reactive at 1200 K, however, its EEO2 dropped rapidly even at 1200 K. The obvious conclusion is that the diamond NP in Fig. had already evolved significantly toward O2 inertness by the time it was heated to the 1400 K starting point. A similar experiment where oxidation was carried out at 1300 K for another diamond NP is shown in Fig. , with results similar to those in Fig. , i.e., significant initial Rbase, low initial EEO2, slowly declining over time. That NP had been briefly heated above 1500 K just after trapping, thus it also had likely evolved substantially before oxidation was examined. A possible reason why the diamond NPs appear to have evolved at very different rates is discussed below.