Whether it’s a shimmering light fixture or a glittering champagne coupe, crystal imparts Gatsby-esque glamour. Glass, on the other hand, is crystal’s more approachable cousin. Ubiquitous, affordable and durable, glass has a distinct charm all of its own. While it’s no secret that glass and crystal have markedly different reputations, even the most astute glass collectors would be hard-pressed to explain the subtle, yet salient differences between the two. To clear things up—so to speak—we’ve crafted an ultra-clarifying guide, outlining the science (and resulting design styles) that makes these two elements markedly unique.
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What is Glass?
To make glass, glassblowers melt raw, natural materials like sand, soda ash, and limestone at extremely high temperatures. In high heat, glassblowers can pour, blow, press, and mold the liquified glass into virtually any shape. As the molten rapidly cools, glassmakers have limited time to cut the material by hand. Even when hot, glass cuts are relatively sharp, rigid, and brittle.
Glass is also non-porous, meaning that liquid and air can’t move through it. This resistance to absorption and corrosion makes glassware dishwasher-safe and heat resistant—good news for those of us who detest hand washing dishes!
What is Crystal?
Technically a subset of glass, hand-crafted crystal is made with the same natural elements as glass, but includes lead. Because crystal doesn’t actually hold a crystalline structure, crystal glass should really be dubbed “lead glass.” (Although it’s no wonder the name hasn’t stuck around!)
The high lead content raises crystal glass’s index of refraction, which measures the amount it can bend light. As a result, crystal mimics the sparkle of the highly refractive diamond. Crystal glass’s lead composition also makes it softer and more pliant, allowing glassblowers to easily manipulate it. Glassblowers can spin crystal remarkably thin, creating delicate forms and embellishments.
Crystal glass’s sumptuous shine does come at a price. Its porous structure means putting crystal in the dishwasher is discouraged, as the high heat can easily chip or crack it.
Because of the increasing concerns about lead, manufacturers have begun to replace lead in crystal with alternative metal oxides, including magnesium and zinc. With lead-free crystal, there’s no concern of lead leaching into your food; however, you do lose a bit of the luster associated with traditional crystal glass.
How To Tell The Difference Between Crystal and Glass
1. Sound Test
At your next soirée, raise your wine glass and give it a couple of dings. If you hear a reverberating ring, your receptacle is crystal glass—the longer the echo, the greater the lead content. Otherwise, it’s most likely soda-lime glass, which will emit a quick, clunking noise. Another sound test for your repertoire: lightly wet your finger and run it around the rim of your glassware. Crystal glass will emit a subtle sound, while regular glass will not.
2. Light Test
When held up to a light source, crystal glass will refract the light and cast a soft ray of rainbows. Regular glass will not emit this prism-like effect. Make sure to empty your glass of any liquid before executing the test, as water also bends light into color. You can also shine a UV light onto your glass to further illuminate the properties of your piece. Crystal glass emanates a blue-purple tint, while regular lime-soda glass generally emits a dull green.
3. Weigh Up
Because of its lead content, a crystal piece will be heavier than a glass piece of a similar size. Crystal glass will also feel more solid and have a definite “heft” to it. This stands in stark contrast to glass, which is notably lightweight in nature.
4. Crystal Clear
Pour liquid into your receptacle and examine the glass. Standard glass makes the liquid look foggy—the view through it slightly muddled. Crystal, on the other hand, should provide a sharp, ultra-transparent view of the liquid. Again, because of its lead content, crystal is remarkably see-through. The more lead, the clearer the glass. The clarity of crystal makes it perfect for glassware, chandeliers, and decorations.
5. Look at the Cut
Touch the rim and grooves of crystalware and you’ll find that it feels smooth and rounded. Crystal is pliable enough to mend during the manufacturing process, which explains how glassblowers can achieve relative smoothness. Glass, on the other hand, boats a sharper, more rigid cut, and feels brittle even though it’s actually less fragile than crystal.
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Lead image: Design by Brockschmidt & Coleman, LLC / Photo by George Ross