What is Sterling Silver? (SS) 
Sterling Silver is 92.5% (the Federal Standard) pure silver blended with other metals to make it firmer and to help it hold its shape. Still, it is the softest of the three types of trim. With exposure to air sterling will tarnish.
What is Gold Vermeil? (G/V)
Vermeil (French: [vɛʁˈmɛj]) is a combination of sterling silver, gold, and other precious metals, commonly used as a component in jewelry. A typical example is sterling silver coated with 14 karats (58%) gold and has a thickness equivalent to at least 2.5 micrometers.
How do I know if my silver trim is sterling?
Sterling Silver must be clearly marked, but it can be marked in several ways. Sterling is typically marked "solid sterling", "sterling silver", "sterling", or "92.5." This last mark is a reference to the 92.5% pure silver in sterling. It is against the law to incorrectly mark silver content.