How old do you think this plate is? I've read somewhere a plate with an unglazed bottom can be from the kangxi period. Thanks
Unglazed bottoms were made throughout much of the early and mid Qing dynasty, although they were not that plenty.
There are several things that are not typical, so I would recommend to provide (1) a partial picture of a part of the decoration, with good resolution, to view the blue color, (2) the brown other rim and its shape, showing if there is a lip, (3) the foot rim, taken at an angle, showing its cross shape, and (4) a part of the bottom area, to show if it is natural or made to look old. This color is always suspicious.
Dimensions?
The underside decoration could as well be Japanese.