Since at least the Roman era, people have been desperately trying to make imitation gems that look real. Things didn't get good until the 1700's, when "paste" (glass with lead in it) was developed. The components were mixed wet to ensure a thorough and even distribution - hence the name. Encyclopedia Britannica tells me that clear paste gems, like the ones we see in these petite Georgian-era earrings, were made of silica, lead oxide, potassium carbonate, borax, and a tiny dash of white arsenic. The dished silver settings have 9k gold wires which were likely attached in the Victorian era or later.
GEORGIAN (1714 - 1837)
The Georgian Era was named for the English Kings George I, II, III and IV. Within the powerful nations of France and England, fine gemstone jewelry was worn only by the extremely wealthy, and the styles were regal and ornate. As imperialist war raged in the Americas, Caribbean, Australia, and beyond, the jewelry industry benefited: colored gems from all over the empire became newly available.
A mix of artistic influences from around Europe contributed to the feminine, glittering jewels of the era. Dense, ornate Baroque motifs from Italy showed up in Georgian jewelry, as did French Rococo’s undulating flora and fauna. Neoclassical style made use of Greek and Roman motifs, which were newly popular due to the recently uncovered ruins of Pompeii and Herculaneum.
Lapidary methods improved: the dome-shaped rose cut was popular, as was the “old mine cut”, a very early iteration of today’s round brilliant cut. The boat-shaped marquise diamond cut was developed around this time, supposedly to imitate the smile of Louis XV’s mistress, the marquise de Pompadour. Paste—an imitation gemstone made from leaded glass—was newly developed in the 18th century, and set into jewelry with the same creativity and care as its more precious counterparts.
Real and imitation gems were almost always set in closed-backed settings, lined on the underside with thin sheets of foil to enhance the color of the stone and highlight it's sparkle. This makes Georgian rings tough for modern women to wear, especially on an everyday basis: genteel, jewelry-owning ladies of the 18th century were not famous for working with their hands like we are. Nor did they wash their hands as much as we do. Water will virtually ruin a foiled setting, so take special care with your Georgian ring. Very little jewelry from this period is still in circulation, and it's very difficult to repair.