Becoming Unglued

The Carlisle gems were found along with more than 700 items, including 105 glass beads, pottery, weapons, coins, clay figures, animal bones, tiles stamped with the imperial mark and some 100 hairpins. Similar discoveries have been made during the excavation of bathhouses in Caesarea, Israel, and in Bath.

The presence of hairpins suggest that the gems’ owners were probably female, Mr. Giecco said. And dips into bathhouse water may have loosened jewelry adhesives, such as birch bark resin, and caused metal settings to expand and contract. In the steamy environment, the Roman elite may have emerged from their leisurely baths unadorned. The stones were likely flushed into the drains when the pools and saunas were cleaned.

“The bathers may not have even noticed until they got home, because it’s the actual stone falling out of the rings,” Mr. Giecco said.