All you want to know about Crystal!

The word crystal has a magical sound to those who love glass. It is seen as the most beautifull and valuable of all glasses. This adoration of crystal has led to much confusion about the definition of crystal.

Until the 15th century glass was only slightly transparent. This was due to the processing techniques of the glass and also because of impurities in the raw materials which gave rise to coloration of the glass and opacity.
The name crystal leads back to Italian glass makers from Venice who were the first to be able to make totally clear glass and who called their invention ‘cristallo’. They called it ‘cristallo’ after the clear rock-crystal which were found in the nearby mountain range, the Dolomites. 

Rock-crystal. The material after which lead crystal was named

The invention of ‘cristallo’ didn’t come easily. The technique of making glass was taken to Venice around 900 A.D. The famous Venetian glass makers tried to perfect this glass making and it took more than four hundred years to reach the technical know how to make fully transparent clear glass. 

The ‘cristallo’ from Venice was, however, not crystal but ordinary glass. The Venetian master glass makers or in fact the masters from Murano, an island before the coast of Venice where the glass making was concentrated, developed the technology of making clear glass further and from Murano this knowledge traveled throughout the world.    

Amberina crystal carafes 

It is said that in 1675, the London based glass maker George Ravenscroft, after long experimenting, invented lead crystal. What he invented was a very brilliant type of glass through the addition of lead oxide to the raw materials. Probably the same feeling and amazement what made the Venetian glass makers call their transparent glass ‘cristallo’, was the reason that Ravenscroft's glass was soon called crystal. 

Some say that Ravenscroft got the idea from the Italian glass maker John Baptiste da Costa, who was familiar with the well kept secrets of the Murano glass technologies. However through Ravenscroft the glass industry changed and crystal was born.

Ravenscroft’s crystal had some advantages for the glass makers of those days. It was not only superior in the looks, ‘sparkle’, but the melting temperature of crystal was lower than normal glass and crystal was softer than ordinary glass and therefore easier to cut and polish. Crystal became very popular.                      

Cutting of glass was a very popular in the old days, (16th, 18th and 19th century). The popular drinkware, vases, carafs, etc. were all decorated by cutting patterns on the surface. Because lead crystal is relatively soft, cutting and polishing were much easier to do and on top of that was the result article more shining.
Maria Theresa chandelier (Preciosa)

The invention of crystal also opened the way for crystal chandeliers. Lamp pendants in any shape could be ‘easily’ cut and polished to multi-faceted crystals which enhanced the light of a candle (originally) and later the light bulbs. 

Glass beads are one of the oldest glass products in the world. When cut crystal beads became available, the fashion industry had only eyes for those. Especially when Daniel Swarovski invented the semi-electrical cutting machine because this made it possible to produce large quantities of cut crystal beads and rhinestones in all kind of sizes and in a superior quality.

All these crystal products had a high content of lead. The more lead the softer the material and the more sparkling the looks. Usually these cut crystal drinkware, lamp pendants and jewellery parts contained at least 24% lead oxide.
This lead content became more and more a proof of quality and value. In the first half of the twentieth century there was so much confusion about the name crystal, that it was used by everybody for all kind of different glasses.    

Cut crystal beads (Preciosa)

To end all discussions, the European Union made in 1969 some definitions regarding crystal. Glass containing 4 - 10% lead oxide was called 'crystal' (glass). Glass was called 'lead glass' when it contained 18% or more lead oxide and when the content of lead oxide was 24% or higher it was called 'lead crystal'. 

The basic idea was that a higher value was related to a higher lead content. Swarovski's brand name for 32% lead crystal is even called 'silver crystal' and the customers think that this "32%", which is higher than usual, indicates that this Swarovski 'silver crystal' contains more expensive material. This idea what people had about lead content and value was seriously affected when people realized that lead can leach out in drinks, like wine and orange juice, and everybody knows nowadays that lead is poisonous.

Lead ones seen as the quality improving ingredient became a health risk at the end of the seventees.
The European Union, home to a huge crystal industry, redefined the term for crystal: 
"A high quality glass which must have a refractive index of at least 1.520 and a density of at least 2.45 kg/l." 
(Where the refractive index is a measurement for the 'sparkle'.)   
Swarovski crystal jewellery

Driven by health issues and environmental issues and armed by this new definition, the glassware companies have invented all kind of alternatives for lead crystal which they call proudly lead-free crystal. Where before the lead content was a marketing tool, the new marketing tool nowadays is ‘lead free’. 
These new 'crystals' have all in common that they are lead-free, don't contain leachable toxic ingredients, are chemically very resistant against dish washing reagents, are very hard and therefore durable and they all have a good 'sparkle'. For instance Zwiesel Kristall Glas, Arc International, Pasabahce and Ocean Glass produce drinkware made out of lead-free crystal.

All these 'crystals' are perfect alternatives to make stemware, carafes, barware, etc. The wine glasses can be thin but will not break as easily as before when made out of lead crystal. 
However, since these materials are very hard they are not easy to cut, meaning that these materials are no alternatives for making cut crystal ware. 
Companies like Swarovski, Baccarat and Preciosa therefore still use this high content lead crystal because it can be cut and gives the ultimate sparkle to the freshly cut and polished surfaces.
Because their products are not meant for containing food there is no health hazard.     

Green crystal fish by Lalique

In the US the definition for crystal is different. The US calls all glasses with 1% lead content or more, crystal. This definition is more related to the health concerns. Since lead is poisonous it is seen as a health risk and theoretically any lead present in glass can leach out into drinks or food.

There is still much discussion about this leaching of lead, like the contact time before concentrations get too high, etc. This discussion is fed by investigations by several laboratories from which some show high leaching of lead in short times and others show values which give the idea that it is not so much cause for concern.
So if you have a nice set of crystal wine glasses, like the wine glasses of Riedel, then use them wisely and enjoy your wine. 

I hope the above makes it ‘crystal clear’ what crystal is. If you need more detailed and technical information then you can always contact us.

At this site you can read the tales about some famous crystal ware companies.
Check out these crystal ware companies at the World of Crystal.