I just figure the tea set and the signature looks well above average. Because of this my thought about the matting was that it could have some connection to the 18th century fashion of covering the outside of Chinese cups and dishes with a brown glaze. During the early 18th century tea was brewed directly in the cups with their dishes used as lids. I find your pieces very interesting. This information is given as an example of private conversation only and is not intended to be used as a promotion of any individual piece.
All opinions is the authors and is given as such with all hazards of judging anything from a photo.