Cranberry glass: old mild mellow beauty

The name "cranberry glass" is often connected with the Victorian age. But although some of the most beautiful (and expensive!) collectors items date from that period, cranberry glass did already exist long before the Victorian era, and it's still being made today. Cranberry glass has a mild, mellow pinkish red (or if you want, reddish pink) color, which is why it's also called "gold ruby" glass - and indeed, in some cases it represents the color or rubies very well. Cranberry glass has been, still is, and will be, very popular not only for home decoration but also for collecting: many older pieces are extremely valuable and highly collectable!

The sort of glass that is nowadays known as "cranberry glass", was probably first produced in Bohemia (now: Czech Republic) in the early 18th Century. In those days it was commonly called gold ruby glass, a name that still lingers in Europe.

During Victorian times cranberry glass became a "big thing" in the United Kingdom where many styles and designs were developed. Other countries took up or continued production as well, especially from (roughly) 1870 - 1930 when, apart from traditional Bohemia, great lots of cranberry glas were produced in England, France, Belgium, Bavaria and the USA. It was in the latter country that the glass got its most popular name. The American glassworks were mainly in New England where cranberries are grown, and pretty soon the term cranberry glass was used in order to aptly describe it's beautiful color. One of the best known American producers of cranberry glass is Fenton.

Cranberry glass or gold ruby glass is made by adding gold(III) chloride to the molten glass. Tin in the form of stannic chloride, is sometimes added in tiny amounts as a reducing agent. The gold chloride is made by dissolving gold in a solution of nitric acid and hydrochloric acid (aqua regia), thus producing a colloid. Cranberry glass is typically hand blown or molded. The finished, hardened glass is a type of colloid, a solid phase (gold) dispersed inside another solid phase (glass).

The oldest origins of cranberry glass may date back to the late Roman Empire - no one knows for sure. Either way, it was (re)discovered in the 17th century by either Johann Knuckel in Bohemia or by the Florentine glassmaker Antonio Neri in Italy. However, nobody understood the chemistry behind the color, until chemist and later Nobel prize winner of 1925 Richard Adolf Zsigmondy figured out that small colloid gold particles lead to the red color.

A dear myth tells us that cranberry glass was first discovered when a rich noble threw a gold coin into a vessel containing molten glass. Although quite attractive, this myth is indeed a myth, as the gold must first be dissolved in aqua regia (a mixture of hydrochloric and nitric acids) before it can be added to the molten glass. It's a fine story nevertheless!

Like many others, I thoroughly enjoy the looks of cranberry glass objects... but why? The "gold ruby glass" color isn't particularly impressive - in fact it's a rather weak color, a baby-ish pink that normally wouldn't be used on objects for grown-ups. Yet it is the color that "does it", as I found out with a couple of experiments. With the help of a friendly antiques store owner, we switched the cranberry glass parts of a few objects (some Fenton lamps and a couple of silver-framed glass vases) for identically shaped glass parts that were either clear, opaque white, or clear blue. With the clear blue glass as the only exception, the results were very disappointing: eye catchers suddenly became plain, unappealing objects. With the blue glass it was different: still eye catching, but a bit "overdone": the equilibrium between the glass and the fittings/trimmings was gone.

So the answer to my question "It's lovely... but why?", is very plain and very simple: because it's cranberry glass!