Wikipedia
Meenakari is the art of coloring and ornamenting the surface of metals by fusing over it brilliant colors that are decorated in an intricate design. Mina is the feminine form of Minoo in Persian, meaning heaven. Mina refers to the Azure colour of heaven. The Iranian craftsmen of Sasanied era invented this art and Mongols spread it to India and other countries. French tourist, Jean Chardin, who toured Iran during the Safavid rule, made a reference to an enamel work of Isfahan, which comprised a pattern of birds and animals on a floral background in light blue, green, yellow and red. Gold has been used traditionally for Meenakari Jewellery as it holds the enamel better, lasts longer and its luster brings out the colors of the enamels. Silver, a later introduction, is used for artifacts like boxes, bowls, spoons, and art pieces while Copper which is used for handicraft products were introduced only after the Gold Control Act, which compelled the Meenakars to look for a material other than gold, was enforced in India.
Initially, the work of Meenakari often went unnoticed as this art was traditionally used as a backing for the famous kundan or stone-studded jewellery. This also allowed the wearer to reverse the jewellery as also promised a special joy in the secret of the hidden design!