Sterling silver has a fineness of 925 because it includes 92.5 percent silver and 7.5 percent another metal, generally copper. Jewelry silver is an alloy made up of 80% silver and 20% copper (800 fine). Silver plating on metals increases their resistance to corrosion and aging; without silver, aluminum would quickly rust away and zinc would lose its color. Silver has been used for ornamentation and currency since ancient times. It was considered valuable because it is soft and can be easily worked. As early as 3000 B.C., silver was used by peoples as far apart as India and Mexico to make jewelry. In Europe, silver became popular again after the discovery of America, which produced gold in large quantities. The English adopted silver as money and used it as collateral with other countries to avoid any possible conflict over trade agreements. This practice led to England becoming one of the largest consumers of silver until the 19th century. Until the mid-19th century, most silver used in commerce was inode (925). This grade of silver has a higher content of silver than sterling silver but is still considered precious metal. Inode is used in manufacturing coins and other monetary instruments. Stirling is the name given to a silvery-white metallic element that was first isolated in 1848 by James Webster Stirling.