Art and Antiques: How to spot high-quality crystal

When it comes to glassware, most people think that the best way to spot quality is to "ting" the object and listen. But if you educate your eyes to spot a high-quality piece of crystal, you can give your ears the day off.

Why? The sound of a "ting" from a piece of glass is subjective and it may not actually tell you anything about the quality of that piece of stemware. Other factors need to be evident to determine if you truly have the real thing.

Glassware (traditional soda-lime glass) contains about 50 percent silica (sand) and no lead. Crystal contains at least 24 percent lead. That is the basic distinction between crystal and glass.

Sounds easy enough, but it isn't that easy. You remember your mother telling you that nothing worth having is ever easy.

Most of the time, your everyday orange juice glass is made of a material called soda-lime glass, a combination of lime, silica (sand) and soda. It is used for products such as windows and everyday drinking glasses. Most glass made in the United States today is soda-lime glass, and doesn't involve a big investment.

On the other hand, borosilicate glass — called Fire-glass in the early 1900s and now called by its brand name of Pyrex — is a heat-resistant glass that does not break when exposed to extreme temperature changes. It is more expensive than soda-lime glass, and was first introduced for the windshields of railroad trains, to stop window breakage when trains experienced a severe change in weather conditions.

Borosilicate glass is mainly used in laboratories and does not easily corrode. Neither of these types of glass — soda-lime glass or borosilicate glass — is considered crystal because neither has 24 percent lead content.

Crystal is made of silica (sand), lead oxide and soda and it is known to be beautiful and strong. "Crystal" is a term used to describe any glassware that looks fancy or is used in the service of champagne, wine or spirits. It is the choice for spirits and wine connoisseurs because it allows the drinker to assess the color and viscosity of the wine or liquor. If your piece of crystal is very clear, it probably has a greater amount of lead content.

When it comes to crystal, its reflective quality and the 24 percent lead content are most important characteristics. Crystal shows more clarity than a typical piece of soda-lime glass, and its reflective quality is why crystal is used for chandeliers, fine wine glasses and jewelry pendants. Very fine crystal, like those pieces made by high quality firms such as Waterford, may even exceed the 24 percent lead content requirement. Those companies may provide products that are 30 percent lead content or more.

The confusion surrounding crystal is based in history and chemistry. First of all, despite its name, crystal does not have a crystalline structure. And, "crystal" comes from a term (cristallo) coined by Italian glassmakers in the famous Murano glass-blowing center near Venice to define quality glassware which did not meet the European lead content standard.

Crystal is typically thin because it is easier to sculpt glass with a high lead content. Lead lowers the working temperature of the glass, extending the time that a glass blower has to sculpt a piece.

Tips for telling the difference between regular soda-lime glass and crystal:

—Crystal has the following attributes: 24 percent lead content, bright reflective quality, clear overall appearance, silver or silver/purple hue, rainbow prism effect when held up to the light, thinner than regular soda-lime glass and heavier than regular soda-lime glass.

—Crystal with a lead content over 35 percent will actually sparkle.

—Place your thumb into the cut design of the piece and, if you move your thumb around and you get cut, then you have a piece of cut crystal. Crystal will take on the properties of sharp cutting.

—Fine glassware may contain some lead content, but if the 24 percent lead content level is not reached then a manufacturer cannot, by law, call that piece "crystal."

Celebrity Ph.D. antiques appraiser, author and award-winning TV personality, Dr. Lori is the star appraiser on the Discovery channel's "Auction Kings." Visit DrLoriV.com, Facebook.com/DoctorLori, @DrLoriV on Twitter or call (888) 431-1010.