| avventurina | an especially prized glass paste, invented by Murano glassmakers during the first half of the 17th century. It was given this name because its manufacturing process was tricky and of uncertain success, for even the most experienced glassmaker, and was therefor a ventura or chance. The preparation of "aventurine" is long and delicate, resulting in the formation of small copper crystal, foliated and shining. It was kept a closely guarded secret across the centuries by a small number of skilled glassmakers. The glass is removed from the furnace in blocks, after having been slowly cooled, and its characteristic apperance can be seriously impaired during remelting. Once cold, it is cut like a hard stone or worked hot with special care. Ordinary "aventurine" is a brownish colour with stelle, whilst an even more highly valued type, known as verderame, takes on a copper green colour of superb effect |
Technical Glossary 
