On a microscopic level, crystal glasses and stemware have a coarser and more porous surface than ordinary stemware and glasses. The coarser surface helps to release and enhance the special aromas of wines and spirits.
That's why crystal stemware and glasses are so highly valued by most wine drinkers.
And also used in hotels and restaurants around the world.
However, a crystal glass is softer and more delicate on the surface than an ordinary glass.
Therefore it's easily scratched.
Even dust can act as an abrasive and cause scratches.
Mouthblown or handblown glasses
Mouthblown or handblown glasses often have small air bubbles - you can see them if you hold a glass up to strong light.
They may also have socalled flow lines and chill marks, which are indentations on the surface of the glass.
These are not flaws in the glass, but inevitable in a mouth blown or hand blown glass - signs telling you that the glass is hand made.
Even fine quality crystal may have air bubbles, chill marks and flow lines.
Much crystal contains lead oxide
The lead oxide increases the density of a glass thus making it more clear, reflective and brilliant.
However, environmental restrictions on the use of lead have led to the development of lead free crystal that's just as good as the original lead crystal.
Today you may find both lead and lead free crystal stemware and other glassware.