In its beginning, mercury glass was considered a knockoff of the real silver furnishing the houses of the well-to-do, says Diane Lytwyn, author of Pictorial Guide to Silvered Mercury Glass (Collector Books, $24.95). Now, the well-to-do are collecting it.
According to Lytwyn, mercury glass was first produced in Bohemia (now the Czech Republic) and came to popularity in the 1850s. Contrary to its name, elemental mercury was not used to produce tableware. In fact, "silvered glass," an alternative title for mercury glass, better describes how it was produced. Basically, glass was blown double-walled and then filled with liquid silver.