Most dealers and collectors define antique glassware as items dating back two generations or more. That means many items in your grandmother's china cabinet, including Depression glass, will be considered antique, if you are an adult today. Identifying reproductions of antique glassware requires keen eyesight and careful tactile examination of the item, as well as some knowledge of how the original antique was manufactured and how reproductions differ.
Know the various names and manufacturers of the antique glassware you are trying to identify. You can find the information and many close-up photographs in numerous guides by well-known glassware experts. These may be found at your local library, bookstores and in most antique stores. Consult the guide any time you have a question about an antique's identity.
When shopping for antique glassware, keep a list handy that reports the colours and sizes of pieces in which your antique glassware was manufactured. For instance, the Federal Glass Co. produced "Sharon" glassware, also known as Cabbage Rose, from 1935 until 1939, in amber, crystal and green. The green Sharon butter dish was valued at about £52 recently. An observant collector noticed an opalescent blue Sharon butter dish at an antique show some years ago and knew immediately that the glassware had little value to a collector. She knew Sharon was never manufactured in blue.
Feel the antique glassware all over to check for telltale signs of newer manufacture. For instance, the Hocking Glass Co. produced "Mayfair" glassware, also called Open Rose, between 1931-37. A yellow antique "Mayfair" cookie jar could fetch more than £552 at an auction today. Identify an authentic antique by its base. Glass cookie jars produced at that time were made with a slightly raised circular rim on the jar's base. Newer reproductions are perfectly smooth on the bottom.
Keep a measuring tape in your pocket or purse when shopping for or trying to identify authentic antique glassware. For example, the antique "Cherry Blossom" glassware was made by the Jeannette Glass Co. from 1930-39. Its double-handled tray has a bottom-glass depth of 3/16 of an inch. A newer fake version weighs nearly a half-pound more and has a glass thickness of ¼ inch.
Know the sizes, inside and out, of various pieces in each collection that interests you. Fake salt shakers often appear to be the same size when only the exterior is measured, but in fact have a lot of extra glass inside so that the actual depth can vary by up to an inch. Always measure any piece that you think might be a fake.
Know other unique identifying characteristics of the authentic antique glassware, such as whether a cereal or berry bowl was originally made with or without handles, how many threads should be found in a salt or pepper shaker lid, or whether a flower in the design is supposed to be open or closed. Know whether a plate rim was scalloped or smooth when manufactured as an original. Inspect designs and patterns closely with a magnifying glass.
Know the differences between different types of antique glass manufacturing techniques. Antique cut glass, for instance, was cut by hand. Its edges are sharper, and its hand-chiselled designs are not as accurate as the pressed glass made by machine.
Consult old advertisements and catalogues for information. These may be found in most libraries. Most catalogues from the early years of the 20th century provided detailed descriptions of the glassware they sold. Make copies of antique glassware ads that interest you, and carry a copy of the ad with you when trying to identify antique glassware.
Know your dealers and buy antique glassware only from someone you know is reputable. Know price points for genuine antiques so you can more easily spot fakes being marketed at high, but not market-value, prices.
Never buy antique glassware from a photograph or from an unknown distributor.