When and Where was lead crystal first produced?

When and Where was lead crystal first produced?
Probably by Ravenscraft in England during the 17th century. When lead oxide was added to the "frit", there were often impurities in it and, at first, there wasn't any knowledge of how much should be added. Accordingly, glass from that period often suffers from what is known as "crizzling". This is a gradual disintegration of the glass, typically through the loss of its transparency via a sort of white clouding of the metal.