I can see more details with an inspection microscope at 50x: I can see the recessed walls of the "D" are frosted for both small D & normal D. The mirror surface at the bottom of the D have striation marks as well as small blisters (due to chemical etch?) The normal D has more pronounced "blisters" than the small D.
Update:
When I said the sidewalls of "D" are frosted, I mean the walls are not mirror-like as in the bottom of the "D". The normal "D" has more noticeable vertical grooves along the sidewalls. The sidewalls of the small D are quite smooth.
For the normal D, the bottoms of the "D", the "10 Yuan", and the "1 oz Ag .999" all are peppered with roughly same size blisters and the striation marks run the same direction. For the small D, the blisters are also present in the bottoms of all texts except they are much smaller. The striation marks run the same direction for "D" and "10 Yuan", but I couldn't find striation marks on "1 oz Ag .999".