How to Identify Antique and Vintage Glass

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Here's your guide to identifying glass—and deciding if it's rare or valuable.

Glass is seemingly everywhere, but not all glass is created equal—and just how unequal can be a bit of a mystery. If you have acquired glassware from a grandparent, estate sale, or antique or secondhand store, you may be a bit curious about how old it really is or the story behind it.

Is it a collectible? How do you identify glassware patterns? What antique glassware brands should you be aware of? What are the most rare kinds of glassware? And how can you identify what kind of antique or vintage glass it is? We turned to Samantha Robinson, consignment director of decorative arts and design at Heritage Auctions, to lend her expertise on the subject.

Similar to furniture, glassware that is more than 100 years old is considered antique, while anything that is at least 40 years old is considered vintage. Regardless of a piece's exact age, you can flawlessly style it throughout your home, but a keen eye might also be on the lookout for the hottest antiques to buy now and things designers recommend always buying vintage.

Perhaps the first thing to know is that it is difficult to discern what kind of glass a piece is, according to Robinson, because glass has been produced in so many different periods. "Many times different firms were responding to one another and their product, or later on we see individuals and companies trying to replicate glass of an earlier time," she explains. That said, there are still steps you can take to investigate.

Take some time and look closely at the piece's shape, surface, weight, and quality—all potential clues for you. "Is the glass transparent or opalescent or iridescent?," Robinson asks. "Is there any decoration that might give away what it is or who may have made it?"

Any Signatures or Marks

Look to see if the glass has been signed or marked. Usually signatures are found on the underside of glass, but sometimes you can find one on the body. Signatures are sometimes faint too. If you are having trouble reading it, Robinson recommends rubbing the glass with a charcoal pencil so you can see the signature better.

Comparison to Online Resources

Most auction houses like Live Auctioneers retain and post their auction records on their websites, so you can look up recent auction results and compare your piece to others that have sold. You can find a lot of resources online put together by glass collectors.

The most notable one that Robinson uses herself and recommends is loetz.com, a site where collectors of that form of art glass have documented the history of the firm and provide examples of each type of glass they produce. Check Facebook as well. "There are Facebook groups for nearly every type of glass imaginable," Robinson says.

Professional Consultation

If you think a piece might be valuable, you can reach out to an auction professional to determine if it's one that might be auction-worthy.

While glass can originate in most any time period, now often people are finding glass in their grandparents’ collections or others from that era that is from the late 19th century and early 20th century—a time Robinson argues is "the apex of the medium"—so she provided us some guidance on what to look for from that time.

First off, know that 90 to 95% of the glassware you might inherit or encounter in a second-hand shop is very common, Robinson says. The most valuable glass you could find, however, is art glass—pieces not intended to be used practically as vases and such but rather meant to be art alone. Here are a couple of the most notable makers to look for.

Thomas Webb & Sons

In the U.K., Thomas Webb & Sons produced cameo glass in a traditional Neoclassical style, layered and either acid etched or carved to expose a design. Its designs are inspired by Roman glass that was being unearthed and acquired by European at the time, portraying replicated mythological scenes for a new market with new technology.

Tiffany Studios

In the U.S., Tiffany Studios, founded in the U.S. by the son of the founder of Tiffany & Company, Louis Comfort Tiffany, produced a type of glass called Favrile glass, meaning handmade. Tiffany was also interested in ancient glass from Rome and Egypt on which, because it had been buried for so long, the chemical composition of the glass had created this iridescent quality to the glass. Tiffany Studios reproduced that look and, according to Robinson, is viewed today as the foremost glass manufacturer in history, arguably with the highest value.

Most are signed, but there are plenty of pieces by Tiffany contemporaries that produced glass in the same style—and achieved critical acclaim and commercial success— and signed with marks that are hard to identify.

No matter the value your glass has at the end of the day, though, it can become a beautiful and meaningful part of your home.

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