Just a question. Many, if not most pictures of Asian pan tiled roofs, I've seen are, like these, in a grey or greyish green colour. Pan tiling in the Med and in South America usually ranges between, biscuit, ochre and terracotta. You only see greys where mildew has accreted (quite common in tropical parts). I presume that Chinese and Japanese pan tiles are just fired clay, like their European counterparts. That being so what gives them their distinctive hue? Surely it's not just the clay used as it must vary a fair bit from place to place.
Inquiring minds must know and this place is as good as any to ask.