I think the cobalt and bottom rim is fine. The mark looks a lot like other kangxi chenghua mark I've seen but without the double circle. I don't know about the mouth because it looks like there is no wear but I've seen jars online with brownish mouths and others as white as this one.
The color blue looks like it would be 18th century but the top and outside rim should be unglazed and the bottom dose not have the age signs you would normally see, perhaps 20th century.