I've seen examples with almost identical decorations but with different arms. Does it look like it could be from the qianlong period?
Looks like a fake.
I have seen a lot of Armorial, mostly in books and actions, but not like this and the bottoms were always glazed, I agree with Peter, a fake.
From what I've seen, armorials usually follow the same design features as non-armorial export porcelain from the 18th Century.
Some very large export pieces (platters, chargers, etc.) have unglazed bottoms, but they are usually flat with no rim.
Bokaba