Originally, rhinestones were rock crystals gathered from the river Rhine, hence the name, although some were also found in areas like the Alps, but today the name "rhinestone" applies only to varieties of lead glass known as crystal glass. The availability was greatly increased in the 18th century when the Alsatian jeweller Georg Friedrich Strass had the idea to imitate diamonds by coating the lower side of lead glass with metal powder. Hence, rhinestones are called "strass" in many European languages.