Below is an excerpt from an article by David Whitehouse, the director of the Corning Glass Museum on the history of Roman glass cremation urns.

The use of glass extended from daily life to the grave. In times and places where cremation was customary, mourners would pour libations and sprinkle perfumes on the pyre.

Sometimes the ashes of the deceased were collected in glass urns. These urns were substantially larger than urns of today. The Roman urns had to be able to accommodate the larger remains left whereas today we grind the remains into sand like size of material. Mostly they had a utilitarian look to them because they were placed into a decorative carved stone Columbarium for eternal storage. These might be special cinery urns, occasionally with a perforated, funnel-shaped lid that allowed one to pour libations over the ashes but often a large storage jar was used for the purpose. Many people in the Roman world believed in a conscious existence after death and useful objects, including glass vessels and their contents, frequently accompanied the deceased to their tombs.

In fact, tombs are the source of the majority of the Roman glass objects that have survived intact.