Whether it is Depression glass, Wedgwood crystal, carnival glass, or a one-of-a-kind piece of art glass, antique drinking glasses can come in many colours, shapes and forms. Because of this, it is often hard to identify authentic pieces of antique glass from reproductions or newer glassware. Taking the time to research your piece of glass can help authenticate it, and the research will educate you on how to spot the most valuable pieces of antique glassware to add to your collection.
Look for and identify a maker's mark. Check the bottom of your glassware for an etched manufacturer's marking. The mark can be hard to see if the base of the glass is heavily cut, so you may need a magnifying glass. Identify the mark using a guide for glassware makers. The web site Inkspot Antiques & Collectibles has collected a list of links for help in identifying glass markings. Another good source of information on manufacturing marks is the book "Crystal Stemware Identification Guide" by Bob Page and Dale Frederiksen. Use the maker's mark to further research your glassware to see if it is an authentic antique.
Find guidebooks about antique drinking glasses. Because drinking glasses are a popular collectable, there are many books that give advice on buying, selling and identifying these pieces. Check a library, bookstore, or on Amazon.com for titles such as "English Drinking Glasses 1675-1825" by L. M. Bickerton, "Glass Tumblers: 1860s to 1920s Identification and Value Guide" by Thomas H. Bredehoft, and "Antique Drinking Glasses" by Albert Hartshorne. See if your piece matches any of the pictures in these guidebooks.
Research old catalogues. If you know the manufacturer of your glassware, look at libraries, bookstores, and in Internet stores for reproductions of old manufacturing catalogues. Many glass companies created yearly catalogues of the new glassware they were producing. These catalogues can often be found in book form. Also, if the manufacturer of your piece is still in business, look on the company's website. Many glass makers provide information regarding older patterns and styles that are no longer manufactured.
Learn to spot reproductions and newer glasses. Vintage glasses show more wear than newer ones. Check for small scratches and wear on the bottoms of the glasses to indicate they have been used over the years. Compare the weight of your glass to a new one. Older drinking glasses are often heavier. Consult a book such as "How Do You Know It's Old?: A Practical Handbook on the Detection of Fakes for the Antique Collector and Curator" by Harold Leslie Peterson to learn more about how to spot reproductions or newer versions of drinking glasses made from antique moulds.