Better pictures have helped
Are you sure they didn't visit the Cantonese area of China, too ? Although both countries copied each others antiquities.
Appears to be some grain there and looks more like ivory in the better light.
I catalogued this Cantonese sewing / work box for auction. It was made c1840 and the quality and detail was superb
Close up of one of the panels. Note that the figures were miniscule yet still detailed with features.