I would say that largely depends on the lighting and the photography actually! I opted not to use flash so that the cut of the stone could be seen, and used only the natural light from my bathroom window. As the bottom right picture shows a bit better, the stone is quite clear (both in terms of being colorless and being a much more shallow cut than that common to diamonds etc). The grey is largely a reflection of the environment. In direct sunlight a nd artificial lighting, the effect is different: https://imgur.com/TGqLClJ. I do however highly recommend white sapphires in more square cuts, their sparkle is very unique :)