Crystal is a form of glass, but not all glass is crystal. The drink ware in your cupboard are most likely glass, or even more elaborate cut glass -- they're strong, can survive many washings in the dishwasher and probably won't chip if knocked over -- but they are not crystal. Crystal, a more delicate type of glass, is heavier and contains lead. The lead used gives crystal its definition and status.
Glass is made from sand, while crystal is comprised of sand and lead. John Kennedy, head of technical services at the prestigious Waterford factory in Ireland indicates that the lead content in crystal must be a minimum of 24 percent to achieve the crystal definition. Waterford's minimum lead content is 32 percent. Everyday glassware contains 50 percent sand and no lead. But some American manufacturers produce glass with less than 24 percent lead and refer to it as lead glass.
Feel the Difference
Crystal is heavier than glass due to its lead content, but glass is often thicker to the touch than crystal. A delicate, paper-thin rim indicates the piece is crystal since it can be blown thinner than glass. Run your fingers along the cuts in the glass or crystal piece. Crystal etching results in rounder edges, while cut glass has sharp, edgier cuts. When blowing crystal, the high lead content makes it softer and easier to shape and mold. The creative and varied shapings found in crystal are a direct result of its lead content.
Hear the Difference
Gently swipe your moistened finger around the rim of a glass or crystal goblet. The musicality you hear only comes from crystal. When tapped or clinked in a toast, crystal rings clear, while a dull thunk or clunk tells you the vessel is glass. The lead content makes the sound possible, and the more lead, the longer and clearer the tone. If the moistened finger doesn't work, lightly tap the bowl of the glass with a teaspoon to see if it creates a resonant note.
See the Difference
If the drink ware is crystal clear, it more than likely is lead crystal. It may give off a silver hue, which is an attribute of lead crystal. Along with its hue, the greater the lead content, the clearer the glass. Hold a piece of crystal up to the light and a rainbow prism is often reflected off the bowl. This reflective quality is what makes crystal chandeliers shine and the Waterford crystal ball on New Year's Eve in Times Square shimmer.
A Gentle Warning
Because of the high lead content in crystal glasses and decanters, it is advised that storing wine or spirits in a crystal decanter for a prolonged period of time may result in trace amounts of lead seepage from the crystal into the liquid. Short-term use of crystal, such as drinking a glass of wine with a meal, isn't considered dangerous.