Gemma was a semi-precious or noble stone with the shape of a round or oval plate decorated with relief. Gemmas were popular as ornaments or seals in the Roman Empire. In Rome, probably the first to wear a gemma was Scipio Africanus.
They were already produced in Mesopotamia, Egypt and ancient Greece. They played a decorative, and sometimes even religious and magical role. They depicted human and mythological figures, animals, plants or religious symbols. At the end of the Hellenistic period, cheap imitations of gemma in glass began to be made – a great example is the famous so-called Portland vase from the beginning of the 1st century CE.
Cicero mentioned that the Romans often placed famous people of the time, such as philosophers, on rings or cups.