Silver thread

Goldwork is the art of embroidery using metal threads. It is particularly prized for the way light plays on it. The term "goldwork" is used even when the threads are imitation gold, silver, or copper. The metal wires used to make the threads have never been entirely gold; they have always been gold-coated silver (silver-gilt) or cheaper metals, and even then the "gold" often contains a very low percent of real gold. Most metal threads are available in silver and sometimes copper as well as gold; some are available in colors as well.

Goldwork is always surface embroidery and free embroidery; the vast majority is a form of laid work or couching; that is, the gold threads are held onto the surface of the fabric by a second thread, usually of fine silk. The ends of the thread, depending on type, are simply cut off, or are pulled through to the back of the embroidery and carefully secured with the couching thread. A tool called a mellore or a stiletto is used to help position the threads and create the holes needed to pull them through.

Goldwork was originally developed in Asia, and has been used for at least 2000 years. Its use reached a remarkable level of skill in the Middle Ages, when a style called Opus Anglicanum was developed in England and used extensively in church vestments and hangings. After this period it was also used frequently in the clothing and furnishings of the royalty and nobility throughout Europe, and still later on military and other regalia.

Goldwork is currently a fairly uncommon skill, even among embroiderers who work in other free embroidery styles; it is now most commonly used for the highest-quality church vestments and art embroidery. It has always been reserved for occasional and special use only, due to both the expense of the materials and the time to create the embroidery, and because the threads - no matter how expertly applied - will not hold up to frequent laundering of any kind.

...
Wikipedia