Cranberry Glass

Cranberry glass is a form of art glass used primarily for decorative pieces and fine dishware and drinkware.

Cranberry glass is known in Europe as Gold Ruby glass. Though the two names are sometimes used interchangeably, Cranberry glass is actually a paler red than true Gold Ruby glass.

Cranberry glass is made by adding gold chloride (a gold solution made by dissolving gold in aqua regia, a mixture of nitric and hydrochloric acid) to molten glass. The more gold chloride used, the deeper the shade of red in the finished glass. Small amounts of stannic chloride, a type of tin, are sometimes added as a reducing agent. The finished, hardened piece is a colloid: one solid (gold) dispersed inside another (glass).

Because of the cost of the gold and the delicate mixing process, cranberry glass is very difficult to make and a single finished piece is the result of multiple skilled craftsmen and women. Cranberry glass is always mouth-blown, molded, or mold-blown, never factory pressed. Blown glass can usually be identified by the pontil mark on the bottom, molded glass by the mold mark.

According to legend, the secret of making cranberry glass was discovered when a nobleman threw a gold ring into molten glass. Romantic as the story might be, it's false - if there was any gold ring tossing involved, it would have had to be into aqua regia.

Regardless, the secret of making red glass was known to the Romans. The famous Lycurgus cup contains both gold and silver and looks green in reflected light and red in transmitted light.

After the fall of the Roman empire, the secret was lost for centuries before being rediscovered in the 17th century by either the Bohemian glassmaker Johann Knuckel or the Florentine Antonio Neri.

The height of cranberry glass production occurred in the late Victorian and Early Modern eras, from about 1870 to 1930. Cranberry glass is still produced today by such companies as Fenton. Modern cranberry glass is not generally considered to be reproduction glass, even though many of the shapes and styles are similar to those popular in the past.

Fine cranberry glass should be free of ash, chips, or unpolished markings. The pontil - the rough place where a finished piece of mouth-blown glass is seperated from the blowing rod - should be polished as well, not broken or chipped, as should any places where one piece of glass attaches to another, such as a handle.

Though some bubbles and striations are normal in mouth-blown glass, they shouldn't be too large or interfere with the piece's design.

If you are looking for collection pieces, it is best to buy only from a reputable dealer. Novice collectors can sometimes mistake cheaper "cranberry flash" for true cranberry. ALWAYS check the age of a piece if you are unsure - some styles of modern glass can be easily mistaken for Victorian antiques. Fenton glass from the 40's and 50's, before the company began marking their products, are particularly prone to being mistaken for Victorian-era treasures.

True Cranberry and Gold Ruby glass is made with gold, but an attractive shade of red glass can also be made with copper. Most modern, factory-made red glass is made with neither gold nor copper but a combination of either selenium and cadmium or antimony, carbon, and sulphur.

There is also a kind of glass known as "cranberry flash." Much cheaper than true cranberry glass, cranberry flash consists of a thin overlay of color on top of clear glass. The color does not look as deep as true cranberry and there is often a hint of gold iridescence.