Don't know much about this mug. Bought as one of a pair (similar glaze, different design) with the one uploaded next to it. Unmarked, very heavy, 6" tall and 3" diameter at the top. Thick mottled blue glaze - which obscures many of the finer details - over initial thin brown glaze (brown inside apart from the drips inside the rim). Seller on ebay was in the UK and deals with British fine ceramics - though this may be a complete red herring. Design on this looks familiar with the figure-8 mouth and a nice 'leaf' detailing around the top rim. Hobbyist?