Bohemian glass-workers discovered potash combined with chalk created a clear colourless glass that was more stable than glass from Italy. In the 16th century the term Bohemian crystal was used for the first time to distinguish its qualities from glass made elsewhere. This glass contained no lead as is commonly suspected. This Czech glass could be cut with a wheel. In addition, resources such as wood for firing the kilns and for burning down to ashes were used to create potash. There were also copious amounts of limestone and silica. In the 17th century, Caspar Lehmann, gem cutter to Emperor Rudolf II in Prague, adapted to glass the technique of gem engraving with copper and bronze wheels. During the era, the Czech lands became the dominant producer of decorative glassware and the local manufacture of glass earned international reputation in high Baroque style from 1685 to 1750.