How to Identify Flint Glass

Identify the piece of glassware itself. Flint glass was used to make water goblets, wine glasses, tumblers, punch bowls, shot glasses and pitchers, as well as relish dishes, bread plates, jelly compotes, fruit bowls, creamers and other glassware used for entertaining.

Look at the patterns on the item. Flint glass is always patterned, though there are an estimated 3,000 flint glass patterns in existence, 1,700 of which are produced in goblet form. Patterns range from the simple to the elaborate, and can include animals, flowers and fruit.

Observe the color of the glass. Flint glass can have a green or gray tint, meaning it was made with either iron or lime. Glass with a pink or purple color is made with manganese, which was used to negate the green or gray created by the iron or lime.

Check for pattern intricacy, a lack of which indicates a reproduction. The majority of reproductions were made in the 1950s and 1960s, though production began in the 1920s and reproductions were manufactured through the1980s. Most reproductions are documented, according to antique experts from Sean George Pressed Glass &Goblets. Reproductions are also often heavier and thicker than the originals and are sometimes marked with a stamp such as "SM" for Sandwich Museum or "MMA" for Metropolitan Museum of Art.

Look for other signs indicating you are handling flint glass, such as cracks and mold lines. Flint glass was considered to be cheaply mass produced; everyday glassware and cracks in the glass were common, and can be felt from both sides of the glass. Mold lines, or straw marks, in flint glass are not uncommon as well. They appear as thin or thick scratches that can be felt on one side only and were created from the cast iron mold. Bubbles in the glass are another indication, which results from air getting inside the mold during the pressing stage. Bubbles can appear on both original and reproduction flint glass.