Glass cameo vessels, such as the famous Portland Vase, were also developed by the Romans.Modern cameos can be produced by setting a carved relief, such as a portrait, onto a background of a contrasting colour. Alternatively, a cameo can be carved by the traditional, but far more difficult, method directly out of a material with integral layers or banding, such as (banded) agate or layered glass, where different layers have different colours. Sir Wallis Budge alleged that the noun "Cameo" apparently comes from Kame'o, a word used in kabbalistic slang to signify a "magical square", i.e.Today the term may be used very loosely for objects with no colour contrast, and other, metaphorical, terms have developed, such as cameo appearance.This derives from another generalized meaning that has developed, the cameo as an image of a head in an oval frame in any medium, such as a photograph.Conch shells carve very well, but their color fades over time.After 1850 demand for cameos grew, as they became popular souvenirs of the Grand Tour among the middle class.Stone cameos of great artistry were made in Greece dating back as far as the 3rd century BC.The Farnese Tazza (a cup) is the oldest major Hellenistic piece surviving.
The Neoclassical revival began in France with Napoleon's support of the glyptic arts, and even his coronation crown was decorated with cameos.Although occasionally used in Roman cameos, the earliest prevalent use of shell for cameo carving was during the Renaissance, in the 15th and 16th centuries.Before that time, cameos were carved from hardstone.a kind of talisman whereupon magical spells was carved.Cameos are often worn as jewelry, but in ancient times were mainly used for signet rings and large earrings, although the largest examples were probably too large for this, and were just admired as objets d'art.
For example, thinning the top black layer on a three-layer stone changes its color to shades of brown.