Apparently, the diffusion coefficient is delicate to impurities or structural troubles inside the crystal, but that remains to get quantified. For our rough estimates of some time at temperature required to take out the hydrogen from our samples, the hydrogen diffusion coefficient selected is that supplied by Belonoshko et al. https://www.tumblr.com/thegemjournal/759696203354128384/understanding-the-unique-characteristics-of-yellow?source=share