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Ruby glass is the dark red color of the precious gemstone ruby. This popular Victorian color never went out of style and it’s still cherished today as it was then.. According to Naomi L. Over, author of Ruby Glass of the Twentieth Century Volumes 1 and 2 and a collector of over 5,000 pieces of the gem-colored glass, ruby glass is the second most popular collectible.

"I like it for the color," she said. And so, it seems do many other people.

There’s a myth about the discovery of a formula for red glass: Someone dropped a gold ring into a vat of molten glass and it turned red. This is unlikely to be true as experiments have shown that all that appears is a puddle of molten gold at the bottom of the unchanged pot of molten glass. The gold has to be chemically treated before adding it to the glass mixture.

The first written instructions for making gold ruby glass date back to 1685 when Andreas Cassius published his work, De Auro, in which he described for the first time the method of producing a red precipitate of stannic acid with gold, which later became known as the "Purple of Cassius." The high price which this glass commanded and the efforts needed to produce it could hardly be justified by its beauty, but the mysticism connected with gold caused the demand.

However, the Romans made gold ruby glass long before Cassius. The famous Lycurgus Cup, made in the 4th Century AD., contains both gold and silver. An exceptional example of the glass-making skills of the Romans, it now rests in the British Museum in London.

The secret of making red glass, lost for many centuries, wasn’t rediscovered until the 17th Century in Brandenburg, Bohemia. Johann Kunckel, a chemist from a glass-making family, re-discovered how to make gold ruby glass around 1670 and published the results of his experiments in his famous book Ars Vetraria Experimentalis in 1679.

The preparation of red ruby glass is still based on Cassius's instructions: " To make gold ruby glass, include gold chloride, a colloidal gold solution produced by dissolving gold metal in Aqua Regia (nitric acid and hydrochloric acid) in the glass mixture. Tin (stannic chloride) is sometimes added in tiny amounts, making the process both difficult and expensive. The tin has to be present in the two chloride forms because the stannous chloride acts as a reducing agent to bring about the formation of the metallic gold. Depending on the composition of the base glass, the ruby color can develop during cooling, or the glass may have to be reheated to ‘strike’ the color."

Today's studio glassmakers can buy their gold ruby glass in rods from specialist manufacturers. This makes it easier for them, but even more expensive. Most gold ruby glass items made today have a thin layer of gold ruby glass coated with clear crystal. There are other chemicals which produce red glass, but none which have the special magic

of gold ruby. Most red and pink glass today and for many years past is made from selenium. Frederick Carder, working at the Steuben Glass Works, invented a brilliant red glass by incorporating cadmium selenide and zinc sulphide in the mixture. Cadmium sulphide glass, which is yellow, changes to orange when selenium is added and to bright ruby red when sufficient selenium is added.

The number of companies making ruby glass have diminished in recent years. "The environmental agencies have come hard on the manufacturers of ruby glass," said Over. "It cost the Mosser Glass Company, which makes small items like animals, $1.5 million to put in a new chimney."

Other than its inherent color and possible shape, ruby glass pieces aren’t easily identified.

Most Royal Ruby glass wasn’t marked or signed. The glass usually came from the factory with a sticker identifying the Royal Ruby color. When items were marked, the mark is an anchor with the letter H over the middle. "Unfortunately, manufacturers began using stickers in the 1940s, which got washed or pulled off," said Over, who has been collecting ruby glass for nearly 35 years. "The Fenton Glass Company used a silver label with an ‘F’."

Royal Ruby refers solely to the red glassware made by Anchor Hocking. Their initial promotion started in 1938. Some people tend to throw all red glassware into the Royal Ruby category regardless of what company made it. Strictly speaking, Royal Ruby was the term coined by Anchor Hocking to describe the red glassware issued during its late 30̓s early 40̓s Royal Ruby Promotion.

According to Glenda Farris of Boxer Heart Glass of Houston, Texas, the early Depression glass patterns, like Coronation and Old Café sell well, as do any of the vases and Anchor Hocking’s square Charm pattern.

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