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How to Authenticate American Brilliant Period Cut Glass

Updated on August 1, 2011
Two common warning signs of reproduction cut glass are very pointed teeth and obvious flaws in laying out the pattern. In this case the pattern runs completely off the glass.
Two common warning signs of reproduction cut glass are very pointed teeth and obvious flaws in laying out the pattern. In this case the pattern runs completely off the glass. | Source

Until about 20 years ago it was relatively easy to separate modern cut glass from antique cut glass because differences between new and old were fairly obvious. Then, in the early 1990s, new cut glass became increasingly similar to vintage pieces made during the American Brilliant Period, a time spanning 1880 to World War I. This new cut glass from the last decades of the 20th century has become so widespread that even experienced dealers and longtime collectors often have trouble separating new from old. In this article, you’ll learn some simple reliable tests you can perform anywhere to identify the fakes and confirm the age of authentic pieces.

American Brilliant Period (ABP) cut glass from the United States was the finest in the world. New patterns and polishing techniques gave the glass never before seen sparkle and reflections which came to be called “brilliant” and gave the period its name. It was made of the highest quality glass and cut by master artisans with years of training. It is the glass quality and evidence of skilled workmanship which are the most important differences between vintage examples and the flood of recent reproductions.

The new mass produced cut glass can generally be detected by four main features: wheel marks, shapes of teeth, overall glass quality and chemical composition of the glass (as tested by ultraviolet light).

Wheel Marks: Rough cuts on authentic ABP cut glass were made with an abrasive slurry dripping on steel or iron wheels. Those first cuts were then smoothed at stone wheels and finely polished with wood and cork wheels. Eight-inch bowls might take 10 to 20 hours of labor. New cut glass, by contrast, is mass produced with high-speed diamond wheels cutting 10 to 20 times faster. Smoothing is generally eliminated in present day reproductions with pieces being polished after the first cutting. Eight inch bowls may take as little as 1 to 2 hours to complete.

Modern diamond wheels leave virtually continuous unbroken parallel ridges and grooves the length of the cut. In the vast majority of new cut glass, these marks are never polished out and remain in the finished piece. These marks can usually be seen by the unaided eye but are especially obvious with the aid of a magnifying glass. Virtually all traces of wheel marks have been polished out of ABP cut glass. If there are some faint lines present in ABP, they tend to be short and broken because they are the result of multiple passes with the old wheels, not long continuous passes as with diamond wheels.

Teeth: Authentic ABP cut glass was made for dining and entertaining and logically had to withstand reasonable amounts of handling, washing and storage. In contrast, almost all reproductions are made as decorative objects and their construction is often illogical with the function of the original piece they imitate. This is most obvious with the teeth on cut glass reproductions. Virtually all new teeth come to extremely sharp dagger-like points. Tips of authentic ABP cut glass teeth were intentionally rounded or squared off as part of the finishing process. Vintage teeth are blunted for two very practical reasons: safety and appearance. Sharp points on teeth would knock off at the slightest touch with a ladle or serving spoon, sending chips of glass into the strawberries or ice cream. After one or two uses, the chipped teeth would look shabby and unattractive.

Overall Quality: Pinhead-size and larger bubbles are rarely, if ever, found in ABP cut glass, but are fairly common in new cut glass. Large bubbles in old blanks caused the piece to be discarded, or the pattern was deliberately cut over the bubble to hide it. Patterns should remain within logical boundaries. It’s common in new cut glass to find overlaps in patterns where elements of one design intersect, overcut, or run over elements of another design. Rays of starbursts and arms of pinwheels, for example, frequently touch neighboring stars and pinwheels in new cut glass. In some new pieces, entire segments of the pattern run off the edge of a blank due to poor planning. Grossly out-of-round circles, stars with wobbly irregular points, unbalanced patterns, and any obviously misaligned cuttings are all warning signs of a reproduction.

Ultraviolet Light Testing: Virtually all authentic ABP cut glass fluoresces candy apple green or yellow green under long-wave (365 nanometer) ultraviolet light, more commonly called black light. Small black lights, six inches in length or less, or of low wattage may only fluoresce thicker areas of glass such as rims and handles. Larger lights—12 to 18 inches—will fluoresce the entire surface of all but the largest pieces. Generally, the darker the room, the more obvious the fluorescence but absolute darkness is rarely necessary to observe the effect. Be aware, though, that 19th and early 20th century cut glass from other countries may or may not fluoresce.

Marks: Never base your judgment of age or quality on cut glass marks. Fake and forged marks, especially acid stamped marks, are so widespread that all marks on cut glass should be ignored. Faked marks are widely found on cut glass reproductions as well as on genuinely old but originally unmarked cut glass.

Although all the tests described above are important, never rely on any one single test. Consider all the factors—wheel marks, teeth, overall quality and black light results—together before making a judgment on age or authenticity. Unless specifically stated otherwise, all references in this article to refer to cut glass of the American Brilliant Period (ABP).

Mark Chervenka for Ruby Lane

Designs in new cut glass have obvious parallel grooves left by modern diamond wheels. Designs cut in authentic ABP cut glass virtually never have any trace of wheel marks.
Designs in new cut glass have obvious parallel grooves left by modern diamond wheels. Designs cut in authentic ABP cut glass virtually never have any trace of wheel marks. | Source


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      Verlie Burroughs 6 years ago from Canada

      I have a lovely old cut glass vase and had no idea how it was made. I will appreciate it more now, thankyou.

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      Krissy 6 years ago

      Thank you! This is very timely since I recently aquired some ABP cut glass from a local estate auction.