A rock crystal locket, mounted with gold and enamels, Italian or Spanish, 1

A rock crystal locket, mounted with gold and enamels; Italian or Spanish, 17th century. There are 9 small indentations carved within the rock crystal, possibly for reliquaries, but more likely we think to store ‘shrimp stones’. These are natural secretions from crustaceans which were used as a medicine to treat stomach and eye ailments. Their medicinal qualities were discovered in the
Middle Ages, and continued to be sold in pharmacies till as recently as the last century. A very rare and unusual piece.