Silver (Ag)

Pure silver has a specific gravity of 10.5
"Fine Silver" is 99.9% Ag
"Britannia Silver" is 95.84% Ag
"Mexican Silver" is 95% Ag + 5% Cu
"Sterling Silver" is at least 92.5% Ag; harder than pure Ag.
U.S. "Coin Silver" is 90% Ag
Vermeil (Vur-MAY) is sterling silver with gold plating.
Crude fineness testing is done with dilute nitric acid. Silver + dilute HNO3 yields a creamy white to brown liquid. Alloys containing Cu, Ni, and brass effervesce and yield a green, yellowish green or bluish green color. More precise technique involves gauging reaction and resulting color with Schwerter solution (HNO3 + KCr2 + H2O).