A technical study of the Royal Clock Salt

The cameo heads on the base of the Clock Salt were examined using digital microscopy. . It was possible to take high-magnification images of the heads and use them for investigating potential materials from which they might have been created. The aim was to discover whether they were made from stone (such as agate or onyx) or shell . During the 15th and 16th centuries, marine cowry and helmet shells were used to make cameos. The digital microscope images showed us the fine details of the carving as well as the characteristic structural features common to the hard, dense shell of helmet shells and cowries.