When I first started making jewelry, I was all about gold. I learned very quickly that gold is very expensive, and that most "base metal" plated gold is really copper with a thin sheet of gold that wears very quickly.

So I turned to silver. Now, sterling and fine silver are also very expensive, but I found "base metal" silver where the coating is over a silver-colored base metal and, with proper care can retain its shine.

Then I went into a retail store and found sterling earrings for a ridiculously low price.  I bought them and found, much to my disappointment, that they quickly began to look dull and dark.

So I began to research "sterling."  I found that when something is marked sterling, it doesn't necessarily mean that the metal is actually sterling silver. It could be a sterling coating over another metal which will behave much like any other plated silver.

So here's the thing.  If you want to purchase sterling silver, look for the .925 sign on the piece. This means that the metal you are purchasing is 92.5% pure silver.

Disclaimer: I am not a metalurgist. What I share here is based on either my own research or my own observation.