Zari

Zari (or Jari) is an even thread traditionally made of fine gold or silver used in traditional Bengali, Indian, and Pakistani garments, especially as brocade in saris etc. This thread is woven into fabrics, primarily made of silk to create intricate patterns. It is believed this tradition started during the Mughal era and the Surat pot being linked to the Haj pilgrims and Indians was a major factor for introducing this craft in India. During the Vedic ages, zari was associated with the grand attired of Gods, kings and literary figures. Today, in most fabrics, zari is not made of real gold and silver, but has cotton or polyester yarn at its core, wrapped by golden/silver metallic yarn.

Zari is the main material in most silk sarees and gharara. It is also used in other garments made of silk, like skirts, tops and vettis.

Persian is where the word originated.

Zari is basically a brocade of tinsel thread meant for weaving and embroidery. It is manufactured by winding or wrapping (covering) a flattened metallic strip made from pure gold, silver or slitted metallised polyester film, on a core yarn, usually of pure silk, viscose, cotton, nylon, polyester, P.P., mono/multi filament, wire, etc. Nowadays, it can broadly be divided into three types. Real zari, imitation zari, and metallic zari.

Real Zari is made from fine silver or gold thread is drawn from silver or gold alloys, which is flattened by passing it under through equal pressure rotating rollers. The flattened silver threads are wound on the base yarn that is usually made of silk. These spools with silk and silver threads are further flattened for electroplating. The threads are then plated with gold by the process of electroplating. The lustre of the gilded threads is further increased by passing them through a brightener. These threads are then wound on a reel.

In ancient times, when precious metals were cheaply and easily available, only real zari threads were produced. Due to industrial revolution and invention of electroplating process, imitation techniques came into existence to cut the cost of precious metals. As copper is the most malleable and ductile metal after gold and silver, silver electroplated copper wire replaced pure silver. Various modern colours and chemicals are used to create/impart a golden hue instead of pure gold. The precious metals and copper too became dearer due to huge demand in various modern industries. Thus, a cheap and durable alternative was invented with non-tarnishing properties. Metallic zari came into vogue replacing traditional metals like gold, silver & copper. This non-genuine modern zari is light in weight & more durable than earlier editions. Also, it has the sought after properties of resistance to tarnishing and knotting.

...
Wikipedia