Calcedonia is both one of the oldest one of the rarest types of glass. It was first developed on Mourn during the mid Fifteenth Century and is generally attributed to the master Angelo Braver whose firm was producing items in Calcedonia in 1460. For 500 years the mystery of calcedonia has fascinated the world. Items made in calcedonia are among the most treasured holdings of the most famous museums. Although Antonio Neri devoted twelve fulI pages to the description of this glass in his 1612 treatise, L’arte vetraia, the uncertainties and difficulties of its production were resolved only by the masters of Murano and lost with the fall of the Venetian Republic. The secret of the production of calcedonia was finally rediscovered by Lorenzo Radi in 1856 but lost again by the turn of this century. In 1977 the master Loredano Rosin, working with his brother Dino, again achieved the miracle of calcedonia, using this ancient and historical glass to produce hand made sculpture of modem style and design.
Calcedonia, as its name implies, is a type of glass that echoes the multicolored striations of the zoned agate. The colors, shades-and markings of the mysterious calcedonia result from a chemical process intrinsic to each batch of glass; a reaction based on the effect of the silver on the other minerals and substances used to make glass. Even today the production of calcedonia is an expensive and unpredictable process, more akin to alchemy than to chemistry. While the action of silver on the other materials generally results in a blend of colors – browns, greens, and hint of blue – the exact shades and degree of striation cannot be controlled and vary from day to day and item to item. Each piece is a unique and irrepeatable work of art combining an ancient technical process with the best of modem craftsmanship.