Lead is the key to glass brilliancy.
You will not find it difficult to differentiate between cut glass and crystal once you clarify the terms. Both of these types of glassware came into being with the addition of lead to the glass-making recipe, an ingredient that gives crystal its brilliancy and cut glass enough softness to withstand the rigors of the cutting process.
Identification
A lead crystal, cut-glass chandelier.
To be called crystal, a high-quality glass must have a high refractive index--a measurement of how much a ray of light bends when passing through the glass. Crystal has an index of nearly 2, compared to 1.5 of ordinary glass. This extra refractive power is due to the lead content of the glass, which also gives it more sparkle. Artisans start with lead crystal vessels to create cut glass. They cut designs into the smooth surface by expertly moving the glass against differently sized, rotating metal or stone wheels to complete a decorative pattern.
History
The oldest glass artifacts ever discovered by archaeologists are from ancient Mesopotamia, dating to the third millennial B.C. The modern formula for lead crystal originated with British subject George Ravencroft in 1676.
The earliest examples of cut glass vessels are of Egyptian design and date to 1500 B.C. Roman, Assyrian and Babylonian cut glass artifacts from the sixth century B.C. have survived to the present day. The art of cutting glass reached the U.S. by 1771, when German immigrant Henry William Stiegel established the American Flint Glass Manufactory in Pennsylvania.
Features
Crystal glass shines more brightly than common glass.
In order to withstand the modern cutting process, glass must contain at least 24 percent lead, which acts as a softening agent. Glass makers mix pure materials with expert precision to get the best result for this specialized glass. Leaded glass of this kind is called crystal. Both leaded crystal before cutting and cut glass have three major features that distinguish them from unleaded glass: They are heavier than non-leaded glass; they resonate with a clear bell tone when tapped; they have a brilliant, clear appearance in comparison to unleaded glass.
The "Brilliant" Period
The "Brilliant" period acknowledged by cut glass experts began in America in the mid-1870s and continued until World War 1. The discovery of domestic high-grade silica sources gave the American cut-glass industry an edge over European competition. American designers created new, unique designs for glass cutting that also contributed to their domination of the world market.
Famous Ties
Pair your cut glass with the finer things in life.
While American cut glass reigned supreme during the Brilliant period, other countries have superseded U.S. dominance in the industry since the mid-20th century. Some of the most well-known and respected lead crystal and cut-glass manufacturers today are Waterford of Ireland, Swarovski of Austria, Baccarat of France and Mikasa of Japan.
Tags: lead crystal, called crystal, crystal cut-glass, cutting glass, cutting process, glass artifacts, glass must