From the Renaissance they began to be made in Italy, reaching the height of their popularity in the mid 19th century, when Rome was the centre of production; there was a Vatican Mosaic Studio from 1576, set up to create mosaic replicas of the altarpieces in St Peter's Basilica, which were being damaged by the humid conditions of the vast and crowded interior. They were popular purchases by visitors on the Grand Tour, easily portable, and often taken home to set into an object there. Typical scenes were landscapes of Roman views, rarely of any artistic originality, and the micro mosaics were small panels used to inset into furniture or onto snuffboxes and similar objects, or for jewelry. Religious subjects were copied from paintings. The very smallest mosaic pieces come from works from the period between the late 18th century and the end of the 19th. Fortunato Pio Castellani (1794–1865) expanded the range of subjects in his work in the "archeological style", copying Roman and Early Christian wall-mosaics. It was even imitated by porcelain painters, who painted faint lines across their work to suggest the edges of tesserae. An object decorated with many small adjacent pieces (tesserae) of inlaid varicolored glass or stone arranged to form a picture or design. For articles of jewelry, the mosaic was usually made in the form of medallions set in pendants, necklaces, rings earrings, parures etc. Such work had been done principally in Italy, some being executed with skill and artistry in the 19th century Wearing micro mosaic jewelry became popular during the Grand Tour period (17th - 19th Century). Members of rich European families would travel around Europe, taking in the sights and cultures of different countries. Italy was a very popular tourist spot as it had a long and prestigious history in arts and culture - a favorite subject in aristocratic circles. It was also a famous glass producer, and canny Italian craftsmen quickly turned their glass making skills to making stunning miniature micro mosaic pictures for their rich visitors. Mosaic work jewelry of this period usually depicted famous Italian landmarks such as the Coliseum and Vatican Square, though occasionally Roman mythology was a subject too. The richest tourists would commission their own mosaics, with animals and famous works of art being favorite subjects. The small size of the micro mosaic was appealing; micro mosaics could be worn on the Grand Tourists continuing journey, or sent back home to loved ones as a kind of fore-runner to our modern postcards. A distinctive feature of micro mosaics is that the tesserae are usually oblong rather than square. The best work can achieve 3,000 to 5,000 tesserae per square inch. The best collections are in the Hermitage Museum and the Gilbert Collection in London. Asia has produced a number of contemporary examples using modern precision machinery to produce the diminutive elements. Micromosaic jewelry Wearing micro mosaic jewelry became popular during the Grand Tour period (17th - 19th Century). Members of rich European families would travel around Europe, taking in the sights and cultures of different countries. Italy was a very popular tourist spot as it had a long and prestigious history in arts and culture - a favorite subject in aristocratic circles. It was also a famous glass producer, and canny Italian craftsmen quickly turned their glass making skills to making stunning miniature micro mosaic pictures for their rich visitors. Mosaic work jewelry of this period usually depicted famous Italian landmarks such as the Colloseum and Vatican Square, though occasionally Roman mythology was a subject too. The richest tourists would commission their own mosaics, with animals and famous works of art being favorite subjects. The small size of the micro mosaic was appealing; micro mosaics could be worn on the Grand Tourists continuing journey, or sent back home to loved ones as a kind of fore-runner to our modern postcards. For the passionate micro mosaic collector two books written by Mrs. Jeanette Hanisee Gabriel definitely recommended !!