The glassware industry has existed for millennia. The first true glass objects were beads originating in Egypt or Mesopotamia.  Recognizable forms of glass tablewares common today have roots in fifteenth century Venice. The invention of cristallo, a clear glass that resembles crystal, made it possible to engrave delicate designs and create extravagant glass stems. It became a major export of Venice and spread quickly throughout Europe. In 1571, the Venetian Giacomo Verzelini produced the first Italian-style cristallo in England. 
Between 1571 and the end of the English Civil War in the mid-seventeenth century, England issued few patents to manufacture or import glass. Glass was still being frequently imported into England until a man named George Ravenscroft created and perfected a higher quality of glassware derived from lead oxide or lead crystal. England could then rely less on foreign glass and export more products to places like the American colonies, which until this time received mostly Venetian and Flemish glassware. 
Individual factories produced distinctive styles of glassware, however, archaeologists rarely recover whole specimens. Luckily the sturdiest part of a glass is the most identifiable, the stem. Characteristics used to identify and date glass stems include design, form, color, and composition. This is the easiest part of glassware to manipulate without compromising the integrity of the glass itself. Before the second half of the seventeenth century, individual glassmakers can be discerned by their designs through personalized elements in their glass stems.
By 1696 the English glass industry grew and rid themselves of elusive patents and monopolies which dominated the prior century and limited glass production. There were so many factories throughout England in the early eighteenth century that individual manufacturers could no longer be completely identified through the glass stems; however, overall trends can be seen. Ravenscroft and his successors continued to create products that were reminiscent of the elaborate Venetian style of layered shapes in the stem creating ornate silhouettes. The late seventeenth century brought cleaner lines with rounded edges that resembled a mushroom, or molded pedestal stems that even had political slogans like “God Save the King” commemorating the ascension of King George I. 
The American colonists’ tastes in glassware changed a little more slowly than in England. The eighteenth century saw a shift in the desired style of glass stems. Heavy lead bases of the past were abandoned in favor of a more delicate balustroid form. The weight of these glasses raised concerns with the introduction of the Glass Excise Act of 1745, which raised prices of raw materials used in glass making. 
With a higher price on glass, but with a desire for a more ornate style, glass makers popularized the “air-twist” stem. While this design retained the popular and simple shape of the plain glass stem, it also had a more designed look. The “air-twist” is made by creating air pockets within the glass as it is heated and then drawing them out to create spiral patterns. One such Air Twist drinking glass stems was recovered at the Old Colchester Park and Preserve (see picture above). The exact year of the “air-twist” or “wormed stems” introduction is unclear but most assume it to be around 1730 and were produced until about 1760.
The evolution of tableware in the American colonies during the Seventeenth and Eighteenth century is in many ways a direct reflection of the English glassmaking industry. The presence of an “air-twist” glass stem on an American site suggests that this site could be as old as the stem’s first appearance around 1730. But this does not mean the glass was produced domestically as there was not a strong glass making industry in America until the mid-eighteenth century. Meaning much of the glassware found in early American archaeological sites were imported.
 Encyclopedia Britannica, Glass, Glass Making Over the Centuries. (2016). https://www.britannica.com/technology/glass
 Hume, Ivor Noël. A Guide to Artifacts of Colonial America, Drinking Glasses and Decanters. Pg 184-185. (1969) University of Pennsylvania Press.
 Hume, Ivor Noël. A Guide to Artifacts of Colonial America, Drinking Glasses and Decanters. Pg 186. (1969) University of Pennsylvania Press.
 Hume, Ivor Noël. A Guide to Artifacts of Colonial America, Drinking Glasses and Decanters. Pg 189-190. (1969) University of Pennsylvania Press.
 Hodge, Scott A. The Tax Policy Blog. Lessons for the U.S. from England’s Glass Excise Acts of 1745. (February 23, 2011). http://taxfoundation.org/blog/lessons-us-englands-glass-excise-acts-1745
Encyclopedia Britannica, Glass, Glass Making Over the Centuries. 2016. https://www.britannica.com/technology/glass
Encyclopedia Britannica, Venetian Glass. 2016. https://www.britannica.com/art/Venetian-glass#ref286072<__URLSTART__https://www.britannica.com/art/Venetian-glass>
Hodge, Scott A. The Tax Policy Blog. Lessons for the U.S. from England’s Glass Excise Acts of 1745. (February 23, 2011). http://taxfoundation.org/blog/lessons-us-englands-glass-excise-acts-1745
Hume, Ivor Noël. A Guide to Artifacts of Colonial America, Drinking Glasses and Decanters. (1969) University of Pennsylvania Press.
18th Century Glass, The Wonderful World of Georgian Glass, History. (2016). http://18cglass.co.uk/index.php?main_page=page&id=1