What is an opaque twist stem?

An opaque twist stem contains fine threads of white or coloured enamel glass encased within clear lead crystal. Makers created this effect by arranging enamel rods in a mould, heating them, and twisting the molten metal as the stem was pulled. These stems appeared in mid-eighteenth-century production alongside air twists. They catch the light differently from clear glass due to the opaque threads running through the centre.

Were coloured wine glasses common in the Georgian period?

Coloured glass became increasingly popular toward the end of the eighteenth century and into the Regency period. You will find pieces in Bristol green, amethyst, and deep blue. Earlier eighteenth-century glasses were predominantly clear lead crystal, while coloured vessels like roemers and tinted wine glasses emerged in strength around 1800. These hues were achieved by adding metallic oxides to the molten batch.

How can I tell an air twist from a standard stem?

An air twist contains a continuous spiral of tiny elongated bubbles trapped inside the solid glass stem. If you rotate the glass under a light, the internal threads appear to move and refract the illumination. Standard plain stems are solid and transparent without internal patterns. Air twists require considerable skill to pull evenly from the molten batch without distorting the imprisoned air.