How to Identify Types of Crystal & Glass: Cut vs. Pressed

Clinton, TN – JD’s Realty & Auction. There are many different types of Crystal and Glass and knowing the difference between the two and being able to distinguish between cut and pressed crystals and glass is imperative to correctly attributing each piece. First, let’s look at what makes Crystal, Crystal. The name is derived from the Italian term “Cristallo”, which was used for high-end hand-blown glass in Murano, Italy. Crystal will have a definite, clear ring when tapped or struck, much like a bell. The longer and clearer the ring has the higher quality the crystal. Crystal is a type of glass that contains strengthening minerals like lead-oxide, potassium carbonate, and silica to make the material durable. The added strength allows the crystal to be molded into thin, delicate shapes. Because crystal contains lead or other metals, it tends to be heavier in weight than a standard glass of the same design. Crystal is also able to refract light while glass will typically lack that ability.

Light refraction on crystal

Glass, on the other hand, is a transparent material that can be melted down and molded into solid shapes. It is made from sand, soda ash, and limestone, but other minerals can be added to manipulate its color, durability, and thickness. Glass is often slightly foggy in appearance and can typically feature a tint based on the ingredients in its composition. It can have a green tint if made with iron or a blue tint if made with soda-lime. Glass will have a dull chime rather than a clear ringing sound. Since glass hardens more quickly than crystal, it offers little time to be cut by hand. The material is generally too hot to manage with gloves so the glass is typically bent into shape while hot or blown into a mold. Any cuts on the surface are usually sharp, rigid, and brittle.

Multi-colored Antique Glass Bottles

There are fairly straightforward means to tell if a piece of glass has been cut, pressed or press-molded. Cut glass and crystal will have sharper detail with a more defined pattern, whereas pressed glass will be smoother and worn to the touch. When patterns are cut onto the surface of a glass object by the hand using powered cutting wheels only then does it become definable as ‘cut’. Cut glass and crystal will not have any mold marks or seams. Some molded pieces of a higher quality MAY NOT have seams if the piece has been smoothed.

Seams on antique bottles

Crystal basket

Cut glass designs can most easily be distinguished from blown-molded and press-molded glass designs by simply running the fingers over the edges of the design. Molded glass designs are rounded and smooth and this can be felt. They feel soft, not the way cut glass feels, at all. Cut glass designs will feel sharp and crisp to the touch. Pressed pattern glass does not reflect light from its surface in the same way as cut lead glass.
Using these guidelines and techniques, you should be able to determine whether your piece is Glass or Crystal and further determine whether the piece is truly a cut piece or is molded.