Murano was a commercial port as far back as the 7th Century, and by the 10th Century it had grown into a prosperous trading center with its own coins, police force, and commercial aristocracy. Then, in 1291, the Venetian Republic ordered glassmakers to move their foundries to Murano because the glassworks represented a fire danger in Venice, whose buildings were mostly wooden at the time.
It wasn't long until Murano's glassmakers were the leading citizens on the island. Artisans were granted the right to wear swords and enjoyed immunity from prosecution by the notoriously high-handed Venetian state. By the late 14th Century, the daughters of glassmakers were allowed to marry into Venice's blue-blooded families. (This was roughly equivalent to Archie Bunker's daughter being invited to wed a Cabot or a Peabody.)
Such pampered treatment had one catch: Glassmakers weren't allowed to leave the Republic. If a craftsman got a hankering to set up shop beyond the Lagoon, he risked being assassinated or having his hands cut off by the secret police--although, in practice, most defectors weren't treated so harshly.
What made Murano's glassmakers so special? For one thing, they were the only people in Europe who knew how to make glass mirrors. They also developed or refined technologies such as crystalline glass, enameled glass (smalto), glass with threads of gold (aventurine), multicolored glass (millefiori), milk glass (lattimo), and imitation gemstones made of glass. Their virtual monopoly on quality glass lasted for centuries, until glassmakers in Northern and Central Europe introduced new techniques and fashions around the same time that colonists were emigrating to the New World.