Antique crystal is different from antique glass, though it may look similar and be hard to distinguish. Most antique crystal was made with an infusion of lead, so the pieces of crystal are generally heavier than antique glass, and will have a thicker composition than antique glass in general. There are many types of antique crystal pieces, that were both decorative and utilitarian. Popular items include vases, stemware, candle holders, chandeliers, table settings and jewelry.
Look at the object under a light. Examine the edges of the piece and check for seams. Antique crystal is clear and polished, and will not have visible seams.
Weigh the object. Compare the weight to a similar piece that is made from glass. If the piece is heavier, it may be antique crystal, not antique glass.
Hold the crystal underneath a light to see if there is a rainbow reflection on the crystal. Antique crystal gives off a prism effect when under bright light. Crystal also tends to sparkle more than cut glass.
Look for a mark. Antique crystal, if made by a well-known company such as Waterford or Swarovski, is marked. Take a magnifying glass, and search the entire bottom base for a mark. Make sure to turn the piece over carefully, and place it down on a piece of felt or a clean soft towel, so that the surface does not get scratched or pitted.
Go to the library and look in books that contain pictures of antique crystal. Try to identify similar or exact pieces to yours, and study the characteristics or description in books about antique crystal. Look over your piece to see if there are any similarities. Look in a variety of books and try to choose ones that have color, not black and white, photos. Even though crystal is clear, a color picture will bring out the beauty of the piece, and show correct reflective light that makes antique crystal more pronounced than other types of glass.
Take a teaspoon, and carefully tap it against the side of the piece. Antique crystal will have a "ring" to it, especially leaded crystal.
Look at the overall beauty of the piece. Often antique crystal was used on elaborate pieces, such as ornate candle holders, and more.
Take antique crystal to a specialty appraiser, such as a dealer who is knowledgeable about antique crystal. Go to a local antique mall, and ask if there is a crystal specialist who does appraisals. Try to find a dealer who is accredited with a crystal organization, to get the most accurate and fair appraisal of your wares. Do an online search for one in your area, or look in your local newspaper or phone book.