Introduction
The dominant image of Georgian English drinking glass — the heavy baluster, the air twist, the cut glass decanter — is one of colourless lead crystal: brilliant, clear, and transparent. And for the most part, this image is accurate. The great tradition of English 18th-century glass is a tradition of clear glass, and the forms and decorative techniques that define it — the baluster stem, the twist, the wheel engraving — were all developed to exploit the clarity and brilliance of colourless lead crystal.
But colour was never absent from English glass. Throughout the 18th century, coloured glass was produced alongside the dominant clear tradition — sometimes as a deliberate decorative choice, sometimes as a technical experiment, and sometimes as a response to Continental fashion. Coloured Georgian glasses are among the rarest and most visually striking objects in the English glass collecting field, and their rarity reflects both the technical difficulty of producing consistent colour in lead crystal and the relatively small proportion of coloured glass in total 18th-century production.
This guide explains how colour was achieved in Georgian glass, which colours were produced and when, which are the rarest, and what to look for when collecting.
How Colour Was Achieved in Georgian Glass
Colour in glass is produced by the addition of metallic oxides to the glass batch. Different metals produce different colours, and the specific colour achieved depends not only on the metal used but on the concentration, the composition of the base glass, and the firing conditions. The principal colouring agents used in 18th-century English glass are:
- Cobalt oxide — produces blue, ranging from pale sky blue at low concentrations to deep royal blue at higher concentrations. Cobalt blue is the most stable and consistent of the glass colours and was the most widely produced coloured glass in 18th-century England.
- Copper oxide — produces green in oxidising conditions and red (copper ruby) in reducing conditions. Copper green is relatively common; copper ruby is extremely rare and technically very difficult to produce consistently.
- Manganese dioxide — produces amethyst or purple at moderate concentrations. At very high concentrations it produces a deep black-purple. Manganese was also used as a decolouriser in clear glass, neutralising the green tint of iron impurities.
- Iron oxide — produces green (ferrous iron) or amber/brown (ferric iron) depending on firing conditions. Iron green and amber are among the most common colours in historical glass generally but are less commonly found in deliberately coloured 18th-century English drinking glass.
- Gold chloride — produces the famous gold ruby or cranberry glass — a rich, warm pink-red of great beauty. Gold ruby is technically demanding and expensive to produce, as it requires the addition of gold to the batch and careful control of firing conditions to develop the colour. It is among the rarest of Georgian glass colours.
- Uranium oxide — produces the characteristic yellow-green uranium glass (also called Vaseline glass), which fluoresces brilliantly under ultraviolet light. Uranium glass was produced from the 1830s onwards and is therefore not strictly Georgian, but it is frequently collected alongside Georgian coloured glass.
Coloured Glass in the 18th Century: What Was Made and When
Blue Glass
Cobalt blue is the colour most consistently associated with Georgian English glass, and blue glass was produced throughout the 18th century in a variety of forms. The most commonly encountered blue Georgian glasses are:
- Blue drinking glasses — wine glasses, rummers, and ale glasses in cobalt blue lead crystal, sometimes with gilded decoration. Blue drinking glasses were produced from approximately the 1740s onwards and became increasingly common in the second half of the 18th century.
- Blue decanters — particularly associated with the Bristol glassmaking tradition, blue decanters — often with gilded labels identifying their contents (Port, Madeira, Rum) — are among the most recognisable Georgian coloured glass objects. The term Bristol blue is widely used to describe this type, though blue glass of this kind was produced in other centres as well as Bristol.
- Blue finger bowls and finger glasses — small bowls for rinsing fingers at table, in cobalt blue, are a characteristically Georgian form.
Green Glass
Green glass — produced with copper or iron oxide — was produced throughout the 18th century, though it is less commonly encountered in fine drinking glass than blue. The most notable green glass of the Georgian period is the emerald green produced by some Bristol and Midlands glasshouses in the late 18th century, a rich, saturated green of considerable beauty.
Amethyst and Purple Glass
Manganese amethyst glass was produced in England from the mid-18th century onwards. It ranges from a pale, almost pink amethyst at low manganese concentrations to a deep, rich purple at higher concentrations. Amethyst drinking glasses are considerably rarer than blue examples and are among the more sought-after coloured Georgian glasses.
Opaque White Glass
Opaque white glass — produced by the addition of tin oxide or arsenic to the batch, which creates a white, milk-glass effect — was produced in England from the mid-18th century, partly in response to the fashion for Chinese porcelain. English opaque white glass was sometimes decorated with enamel painting in imitation of porcelain, and the finest examples — particularly those decorated by the Beilby family of Newcastle — are among the most valuable objects in English glass collecting.
Coloured Opaque Twist Stems
The opaque twist stem glasses of the 1755–1780 period represent the most sophisticated use of colour in Georgian drinking glass. The enamel rods twisted into the stems of these glasses were produced in a range of colours — white, blue, green, red, yellow, and combinations thereof — and the coloured opaque twist is among the rarest and most desirable of all Georgian glass forms.
The rarest colour combinations in opaque twist stems include:
- Red or pink enamel — the most difficult colour to produce consistently in enamel rods; red opaque twist stems are exceptionally rare.
- Multi-colour combinations — stems incorporating three or more colours are rarer than two-colour examples.
- Colour and white combinations — a coloured enamel rod twisted with white enamel rods is the most common coloured twist configuration; all-colour twists without white are rarer.
The Bristol Connection
The city of Bristol occupies a special place in the history of English coloured glass. Bristol glasshouses — particularly those of Lazarus and Isaac Jacobs, and later of the Ricketts family — were among the most prolific producers of fine coloured glass in the late 18th and early 19th centuries, and the term Bristol glass has become almost synonymous with Georgian coloured glass generally.
The most celebrated Bristol productions are:
- Bristol blue — the deep cobalt blue decanters, finger bowls, and drinking glasses with gilded decoration that are the most iconic of all Georgian coloured glass objects.
- Bristol green — a rich emerald green glass produced by the Bristol houses, less common than blue but of considerable beauty.
- Amethyst Bristol glass — manganese amethyst in the characteristic Bristol forms.
It should be noted that not all glass described as ‘Bristol’ was actually made in Bristol — the term is used loosely in the trade to describe coloured glass of the late 18th century generally, regardless of origin. Genuine Bristol glass is not marked, and attribution to a specific Bristol house is rarely possible without documented provenance.
Rarity and Value: Which Colours Are the Most Sought After?
Within the field of Georgian coloured glass, rarity and value are broadly correlated with the technical difficulty of producing the colour and the volume of production:
- Gold ruby (cranberry) — the rarest and most valuable colour in Georgian glass. True gold ruby — produced with gold chloride — is technically demanding and was produced in relatively small quantities. Fine examples command very significant premiums.
- Red opaque twist stems — as noted above, red enamel in opaque twist stems is exceptionally rare and commands very high prices when encountered.
- Amethyst — rarer than blue in most forms; deep, saturated amethyst is particularly sought after.
- Beilby-decorated opaque white glass — the finest enamel-decorated opaque white glass, particularly pieces attributable to William or Mary Beilby of Newcastle, is among the most valuable of all Georgian glass.
- Cobalt blue — the most commonly encountered Georgian colour, but fine examples — particularly gilded Bristol blue decanters in good condition — remain highly desirable and valuable.
What to Look for When Buying Coloured Georgian Glass
- Colour consistency — genuine Georgian coloured glass has a consistent, even colour throughout the piece. Streaks, patches, or variations in colour intensity may indicate later production or lower quality.
- Gilding condition — gilded decoration on coloured glass is vulnerable to wear. Assess the completeness and condition of any gilding carefully; worn or partially missing gilding significantly affects value.
- Condition of the glass itself — apply the same condition criteria as for clear glass: examine the rim, foot, and body for chips, cracks, and repairs.
- Attribution claims — be cautious of specific attribution claims (e.g., ‘Beilby’, ‘Bristol’) without supporting evidence. These attributions are rarely provable and are sometimes used loosely.
- Period consistency — assess whether the form, colour, and decoration are consistent with the period claimed. Coloured glass reproductions have been produced since the 19th century, and some are of considerable quality.
The Wonder Room occasionally offers coloured Georgian glass of quality and rarity. Browse our Georgian glass collection or explore further guides in Collector's Insights.