China moulds were popular during the 1800's and early 1900's to make decorative pudding and jellies. The glass ones are newer versions.
This one is made with dark pottery with a chocolate glaze, it is very old.
This is stamped 'Made in England' so it dates it to the early 1900's.
This ironstone mould is quite an early one, the glaze has a slight blue tint to it, so I would guess mid 1800's. The two following moulds are unmarked, more likely date to the early 1900's.
Above is the little one I bought at Y's Buys.
I have used the glass ones to make jelly for the kids, but because they we only packet ones, not made with the original gelatin recipe, they were not solid enough to turn out onto a plate. They still tastes good though.