People have been using hardstones in jewelry since forever, so lots of different names have developed for the same thing. The distinctions between different varieties of hardstones (the science name is chalcedony) are somewhat arbitrary, and are for the most part based purely on visual distinctions, not any actual difference of the mineral’s composition.
Victorian 15k gold and agate seal ring, at Gray & Davis
Early 20th c. 14k gold, blue chalcedony and diamond cluster ring, at G & D
Victorian 18k gold and moss agate dangle earrings, at G & D
Victorian 10k gold, bloodstone and carnelian fob, at G & D
Victorian 10k gold, diamond and onyx ring, at G & D
Arts and Crafts 14k gold and carnelian ring with enamel, at G & D
Because we are nerds, we made this flow-chart to help explain how the tangled terminology fits together:
The Victorian "Remember" seal ring, in 15k gold, also has a fun surprise, which we captured on video!