Naqvi in A Study of Buddhist Medicine and Surgery in Gandhara 2011: 46 also mentions glass tiles found at the Dharmarajika Stupa, Taxila. He presumes they are imported.
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In the northern Indic regions of what is now Pakistan and Afghanistan, there was a substantial number of glass objects found at Begram and some blue glass blocks (paving tiles?) around the stupa at Butkara I in Swat. The Begram material is probably imported but the big blocks of blue glass at Butkara I may have been produced locally.
The Begram material is published in the J. Hackin: Memoires de la Delegation Archeologique Francaise en Afghanistan, Recherches Arceologiques a Begram Chantier No. 2 (1937), Text and Planches (2 vols) and Nouvelles Recherches Archeologiques a Begram (ancienne Kapici) (1939-1940) Text and Planches (2 books).
I am not sure of the blue glass from Butkara I was ever published.
John C. Huntington