Sterling silver, also known as standard silver, is a silver alloy consisting of 92.5% silver and 7.5% copper. It is traditionally used in the manufacturing of jewelry and silverware.
Harder than pure silver…
“In the US, only an alloy consisting of at least 92.5% fine silver can be marketed as “silver” (thus frequently stamped 925). Sterling silver is harder than pure silver, and has a lower melting point (893 °C) than either pure silver or pure copper. Britannia silver is an alternative hallmark-quality standard containing 95.8% silver, often used to make silver tableware and wrought plate. With the addition of germanium, the patented modified alloy Argentium Sterling Silver is formed, with improved properties including resistance to firescale. Sterling silver jewelry is often plated with a thin coat of .999 fine silver to give the item a shiny finish. This process is called “flashing.” Silver jewelry can also be plated with rhodium (for a bright, shiny look) or gold” (Wikipedia).