Crystal is a subset of glass. There are three main criteria for crystal as established by the European Union in 1969:
- a lead content over 24%,
- a density of more than 2.90, and
- a reflective index of 1.545.
John Kennedy, head of technical services at Waterford (the world’s foremost purveyor of high-end crystal based in Ireland) sticks strictly to these guidelines for Waterford crystal.
Outside of the EU, however, this definition is usually disregarded. In the United States, any glass with more than 1% lead content is called crystal.
What makes a glass crystal?
The term “crystal” often refers to glassware that has a more elegant form than the everyday glassware you use at dinner. You bring out “the crystal” for special occasions. However, that is not an official difference between the two. There is actually no universally agreed-upon definition of crystal (beyond the EU definition), but a general rule is that crystal contains lead.
The lead or other minerals used in crystal strengthen the material, so you can have thin and elegant, yet somewhat durable glassware.
How are crystal and glass glassware made?
Crystals are pure elements with an orderly pattern of atoms, molecules, or ions. Crystals occur naturally, but can also be formed by man though a mechanism of crystal growth called crystallization or solidification.
Technically, the application of the term ‘crystal’ to glass is inaccurate, as glass is an amorphous solid. By definition it lacks a crystalline structure. Yet the term has stuck around and remains popular.
Glassware can be made from many materials, most often sand, soda ash and limestone, which are melted at high temperatures. It can also include potash, zinc or barium. The most recent ingredient used is titanium.
As stated above, only products that are 24% lead or more should be technically be called "lead crystal." Products with less lead oxide or other non-lead metal oxides, should officially go by the names " crystal glass” or “crystallin.” Still, they are all often known as the catch-all name, crystal.
Color, brilliance and strength
The color and brilliance of glass varies, depending on its contents. Glass made with iron tends to have a green tinge, while glass made with soda-lime has an aqua tint. Some people find these shades unattractive, but glasses with a greenish hue are usually stronger.
Crystals generally are light in color and mostly translucent. Some clear crystals reflect light into different colors. When held in the right position, the refraction and dispersion of light from crystal will create a rainbow.
Glass also tends to be stronger than crystal, which is why crystal glassware is often only reserved for special occasions (that, plus it should not be put in a dishwasher). The use of lead in the crystal makes the glass soft and malleable, allowing for the formation of detailed patterns and designs you don’t find in glass glassware.
The high lead content is why crystal “rings” when tapped, and is heavier than normal glassware. Depending on the structure, patterns and rarity of the crystals, crystal can be much more expensive than glass.
Beyond the table
Companies like Waterford and Swarovski make crystal vases, bowls, picture frames, candlesticks, clocks, jewelry, chandeliers and more. You can almost always find exquisite crystal items at friendly prices at Legacies Upscale Resale.
Used for awards and recognitions because its heft conveys “momentous” and it can be engraved, crystal is often given as wedding, graduation, new baby and hostess gifts for the same reasons. Since crystal items are frequently used only for celebrations, they are often in like-new condition when donated or consigned to Legacies.