What is 925 Italy sterling silver?

"Italy" denotes the country of origin, and "925" indicates silver at 92.5 percent purity, which is sterling silver. 92.5 percent purity means that the piece is comprised of 92.5 percent silver by mass and 7.5 percent of another metal by mass.

Since pure silver is much too soft at room temperature to be molded into rings, bracelets, charms and other jewelry, 7.5 percent of another metal is needed to harden and strengthen it. The most common metal used to form the silver alloy is copper. Pure silver also tarnishes very quickly, and the addition helps slow down the process. Sterling silver is the purest form of silver that maintains its beauty over time without tarnishing.