According to legend, ruby-red glass was discovered when a noble tossed a gold coin into a batch of molten glass. In reality, it probably happened when glassworkers unintentionally contaminated batches with traces of gold residue or gold nanoparticles that were components of silver additives.
The earliest known ruby glass vessels date from the late Roman Empire and rival the beauty of intricately carved gems. Yet their appeal – along with the secret of their creation – faded within a century.
More than a millennium passed before the quest for ruby glass was taken up anew. Antonio Neri, a 16th-century Florentine glassmaker, experimented with magnesium oxide and copper, a red pigment used for cathedral windows. Further investigation revealed that when clear molten glass is imbued with gold salts (known as chlorides) and re-heated, it assumes a range of jewel-like pink-to-red hues. Better still, the amount of gold needed for even the darkest, deepest red is infinitestimal.
The first European to produce large, evenly-colored, deep red vessels was Johann Kunckel, a 17th-century glassmaker, chemist, and “alchymist,” which is an archaic spelling for “alchemist.” Alchymists had long sought the fabled Philosopher’s Stone, a transparent, glossy red substance deemed essential for transmuting base metals into gold. For hunters of the Philosopher’s Stone, discovering how to create gold ruby glass was not only highly significant, it was wondrous.
Gold ruby glass masterpieces created under Brandenburg patronage feature an extensive amount of cut decoration, such as arches and pointed leaves carved into the glass or features that stand out, dramatically, in relief. The Corning Glass website states, “Seldom has cut decoration been so organically modeled, seemingly floating on the surface.” By the early 1700s, nearly every central European sovereign owned several costly, finely crafted ruby glass goblets, footed beakers, and tankards.
Around the same time, glassworkers in southern Germany were creating simpler, less masterly red-raspberry-hued vessels in forms such as bottles, boxes, and bowls. Many were assembled from gilded-metal mounts and glass components, and some served a dual purpose. For example, certain plates and saucers, when flipped, resembled covers. Beakers were made that looked like bowls, and knobs often formed finials or sections of glassware stems. While the provenance of Southern German ruby glass remains elusive, their uniform appearance suggests a single source.
Interest in gold ruby glassware waned by the early 1800s. However, decades later, Friedrich Egermann, a Bohemian glass decorator, discovered that copper additives would stain glass surfaces a deep red. Sales of ruby glass made with copper soared. Because these pieces were inexpensive enough for mass production but had the appearance of gold ruby glass, they eventually dominated the European market.
This variety of ruby glass was most fashionable during the Victorian era. After wine-colored wine glasses, decanters, and chandeliers studded with tiny ruby glass drops were featured at London’s 1851 Crystal Palace Exhibition, scores of prosperous homeowners graced their parlors with ruby glass candy bowls, vases and table lamps. Collectors sought ruby glass ground jugs, hinged boxes and tea warmers featuring stylized white enamel paintings of children at play. Others focused on delicate gold-painted ruby glass jars, cologne bottles and vanity sets.
By the mid-1800s, ruby glass was becoming popular across America, where it was known as cranberry glass. Through 1915, the Dorflinger Glass Company, based in Brooklyn, New York, created popular pattern-cut dinner bells, punch cups, cigar jars and whiskey jugs. The Indiana Glass Company produced ruby-stained and cranberry-to-clear crystal pitchers, tumblers, sherbets, goblets, serving ware and glassware. Soon after, the Fenton Art Glass Company of West Virginia introduced eye-pleasing red wine coolers, decanters and candy dishes, as well as opulent opalescent bowls, compotes, table lamps and epergnes (centerpieces). Steuben Glass, located in Corning, New York, produced fanciful ruby glass ewers, “candy-caned” vanity jars, majestic vases, lamps and more.
Twenty-first century artisans rely on selenium and rare earth elements rather than gold for making ruby glass. But their beguiling hues, ranging from pale pink to blazing red, continue to fire the imagination.