Around the 3rd and 4th century CE, there was a popular movement in commissioning medallions of glass with engraved gold designs known today as gold glasses.
These have been found in the catacombs in Rome where they were pressed into the morter of the grave.
It seems they were personal use items probably used as a bowl, each one having an individual design. These were often religious (both christian and jewish symbolism) but occasionally secular or pagan images were used.
When the person died, their medallion was used to mark their burial site, perhaps as a marker to the angels to assist in their resurrection.
There may be a couple of different production methods, but in general a glass disc was gilded, engraved with the design and a then a layer of hot glass blown onto the medallion which then formed a dish or bowl.
Some have colored glass for the base. There is a collection of them at the Victoria & Albert museum in London.