? Where was the 1st crystal clear glass made? That mystery was finally put to rest by careful chemical analysis, it was Alexandria, Egypt , as described in an article by the New York times, see link below. https://www.nytimes.com/2020/07/31/science/alexandrian-glass-rome.html In 1987 I hosted a class I was teaching at the Rochester Museum & Science Center to see a special exhibition at the Corning Museum of Glass, GLASS of the CAESARS, the most important exhibition of Roman glass ever assembled. The examples of Roman glass were breathtaking to say the least . The two most important pieces are pictured below. This magnificent piece of cameo glass was made in Alexandria, circa AD 50. While on display at the British Museum in 1845, it was smashed by a mad drunk ! It has since been restored twice . This treasure, also in the British Museum, is considered the most important piece of glass in all antiquity, circa AD 4th century. Not only is it a marvel of glyptic art, but it's an astonishing piece of chemistry. Minute particles of gold were added to the mix of glass giving it the unusual property of being viewed differently with transmitted light and reflected light, like the gemstone Alexandrite. Historians believe the block of dichroic glass was made in Alxandria, and shipped to Rome where it was later carved. For a long time it was believed that this piece of glass was looted from the tomb of Alexander Severus. Historians today cast doubt on that provenance .