I have came across many chinese plates lately. This is one of them. It looks like it has a lot of age to it. White top rim. But the foot rim looks strange. Could it be older than 18th century? Sorry I don't have a photo of the side at the moment.
It is hard to tell by these photo's alone, close up of the bottom showing the pitting up close and the foot at an angle to see the shape and close ups of age signs.