Unguentaria were amongst the most common objects of Roman blown glass: produced in large numbers, they were items of every day use for keeping expensive unguents and cosmetic oils. By the 1st century AD, the technique of glass-blowing had revolutionised the art of glass-making, allowing for the production of small medicine, incense, and perfume containers in new forms. The small body and mouth allowed the user carefully to pour and control the amount of liquid dispensed, and glass was the material of choice for storing the oils because it was not porous. These small glass (or ceramic) bottles are found frequently at Hellenistic and Roman sites, especially in cemeteries, and the perfumes which filled them would have been gathered from all corners of the expansive Roman Empire.
The colouration in this example is very pale, but metal oxides were generally added to glass for variation in colour. Depending on the conditions in the furnace, copper oxides were particularly effective for producing green, blue, or red colours.
To find out more about Roman glass please see our relevant blog post: Collecting Roman Glass.