I recently purchased this larger, chubby, chunky duck at an estate sale and am unable to determine the maker. Measures 8 inches x 8 inches x 8 inches. It is green glazed, fading to brown (drip) at the bottom. At first glance, the mark in middle (raised) appeared to be a backwards 15 or 51, but perhaps I am looking at it wrong and it is another type of logo. Unfortunately there is a chip on the mark. There is also a name or letters inscribed just to the left of it that is worn and not legible, that possibly starts with a V or X. The bill of the duck and eyes are hand painted. Any help, information or leads that anyone can give me would be most appreciated. Thank you!