Silver gilt

Silver-gilt or gilded/gilt silver, sometimes known in American English by the French term vermeil, is silver gilded with gold. Most large objects made in goldsmithing that appear to be gold are actually silver-gilt; for example most sporting trophies, medals (such as "gold medals" in all Olympic Games after 1912), and many crown jewels. Apart from being much cheaper than gold, large silver-gilt objects are also much lighter if required to be lifted, and stronger. Compared to plain silver, for delicate objects like the Nef (illustrated), or those with much intricate detail like monstrances, gilding greatly reduced the need for cleaning and polishing, and so reduced the risk of damage to them. The "gold" threads used in embroidered goldwork are normally also silver-gilt.

Silver-gilt objects have been made since ancient times across Eurasia, using a variety of gilding techniques, and a distinctive depletion gilding technique was developed by the Incas in Pre-Columbian South America. "Overlaying" or folding or hammering on gold foil or gold leaf is mentioned in Homer's Odyssey (Bk vi, 232), and fire-gilding with mercury dates to at least the 4th century BC, and was the most common method until the Early Modern period at least, though dangerous for the workers, as has been known for centuries:

Hang him; a gilder that hath his brains perished with quicksilver is not more cold in the liver

Today electroplating is the most commonly used method. Keum-boo is a special Korean technique of silver-gilding, using depletion gilding. In China gilt-bronze, also known as ormolu, was more common.

...
Wikipedia