Apparently, the diffusion coefficient is sensitive to impurities or structural problems during the crystal, but That continues to be being quantified. For our rough estimates of enough time at temperature required to eliminate the hydrogen from our samples, the hydrogen diffusion coefficient picked is given by Belonoshko et al. (2004), https://sociallweb.com/story3452058/the-best-side-of-sri-lankan-yellow-sapphire