Bezoar stone, which is a calcified concretion found in the stomachs of some animals, was prized for its supposed medicinal properties as well as being believed to act as an antidote to poison. The scarcity of bezoar stones by the 17th century led a group of Portuguese Jesuits working in Goa to come up with a man-made version. These so called 'Goa Stones' were a mixture of bezoar as well as other precious objects believed to have curative powers. Until the beginning of the 18th century, when medical authorities began to debunk the belief in these stones, they could sell for more then their weight in gold.
Small bezoar stones were often mounted, such as this lot, so that they could be worn on a chain as amuletic pendants for protection. It also enabled them to be dropped into a goblet to impart medicinal properties to the liquid or to identify any presence of poison.