It was an English glassmaker named George Ravenscroft who discovered that by combining the ingredients for molten glass with lead oxide, a fine crystal could be made, according to the Society of Glass Technology.
Though Ravenscroft invented the process, the people of Ireland mastered the manufacture of fine crystal. In 1783, more than 100 years after Ravenscroft's discovery, brothers William and George Penrose established their crystal making business in the southeast Ireland port city of Waterford. The company was the predecessor to today's Waterford Crystal, the best-known and best-selling crystal in the world. Other noted manufacturers of Irish crystal include Tyrone Crystal (the first Irish crystal manufacturer), Galway Crystal, Tipperary Crystal, Heritage Crystal and Belfast Crystal.
The process used in making crystal today differs little from the original methods, according to Tyrone Crystal. In a massive furnace heated to 1200 degrees to 1440 degrees C, silica sand, potash and litharge are combined to make molten crystal. Many crystal manufacturers add special secret ingredients to this basic mix.
When the molten crystal has reached just the right point in its heating process, the manual blowing of glass occurs. Master craftspeople quickly and artfully form glowing balls of molten crystal into elegant shapes.
Next, the crystal is rapidly transferred to the annealing oven, which allows the crystal to cool slowly. If the crystal cools too quickly, it can constrict and crack. For a wine glass, annealing takes about two hours. Larger items take much longer.
The cutting of the crystal follows annealing. In fine crystal making, no two pieces are exactly alike because the cutters work from their memories of crystal cuts and patterns. After the crystal is cut, it is immersed in an acid bath, then washed and polished prior to its final inspection.
The result of this long, painstaking and primitive process is the timeless beauty you see when you hold up a piece of crystal and watch the light dance over its surface. Today, the words "fine crystal" are synonymous with "Irish crystal."