Discovered in the seventeenth century by an Englishman called George Ravenscroft, lead crystal production involves the adding of lead oxide powder into molten glass which, is then either blow molded or pressed into shape, depending on the manufacturer?s preference and the complexity of the finished article. To earn the classification of ?Full Lead Crystal? the mixture must contain at least twenty four percent lead oxide and the highest concentration achievable that will allow any kind of workability is thirty three percent. The higher the lead content, the more brilliance the finished article will have. So in order to create a balance between brilliance and workability, most manufacturers aim somewhere in between these two markers.
Once shaping is complete, the crystal is then allowed to slowly cool in an annealing oven prior to any flutes and facets being worked into the moulded product by skilled craftsmen using abrasive cutting tools. For many centuries, the cutting of the flutes and facets into lead crystal was done by hand. However, in the latter years of the nineteenth century, following a visit to the first-ever electrical exhibition in Vienna, Daniel Swarovski embarked upon a mission to invent the first-ever mechanical lead crystal-cutting machine. It took nine years of hard work but, when it was finished, it enabled him and his fellow workers to achieve, with relative ease, symmetry and detail that his contemporaries could only dream of.
The addition of lead oxide gives the finished article more sparkle and the defined edges of the facets and flutes cut into the crystal allow the light to refract and a whole rainbow of colors can be seen. Also, it will ring like a bell when struck gently with a metallic object.
Whilst, due to its lead content, lead crystal use is restricted in some parts of the world. I think that most would agree that nothing else comes close to crystal for giving a dinner table that ?je ne sais quoi?.