An acquaintance of mine recently came into a very interesting item, it is a perhaps marble or jade stamp containing on the bottom the name Charles Sprague, it is actually etched on the bottom, it also has Chinese writing right below the name, I assume it is the name "Charles Sprague" in Chinese. It is approximately 3 in height, there is also a container of the same material containing an ink/wax type substance for stamping documents. I believe Sprague did some work in china documenting plants.
If anyone can help with this I would appreciate it.