Hi John, First I tell you how it is...up to this day I have difficulties dating monochromes. Generally, these are more difficult to identify because they have less points of reference than polychromes.
Therefore, all I say here is my personal opinion.
Points of doubt:
1. The bottom looks much too white and too smooth in these pictures. (If the real thing is snow white, then it is not Tongzhi) 2. Blue Tongzhi marks are relatively rare. 3. Generally, the shape of the pot and the lid (knob) don't look like traditional Chinese wares. 4. Do you see one hole inside, where the spout is attached to the body, or are there several smaller holes to stop tea leaves from entering the spout? (If it is the latter, it is not Tongzhi)
My impression is that this is something modern with a Tongzhi mark, that is all.
