@Alan I love it when you show the art glass from your collection. You have impeccable taste and your examples are stunning. Thank you very much for sharing them!
Wholly machine-made marbles are cut from a stream of molten glass by a shearing mechanism (shears). Each marble has two seams or cut-offs (shear marks), You will find the cut-offs on Popeyes and other spirals on the top and bottom of the spiral.
These are not marbles I am familiar with but they do not look like American marbles to me - maybe Vacor (Mexican), and I now wonder if the glass is intentionally frosted.