Examine the inside edge of your ring for hallmarks and maker's marks, which are symbols, letters, words and/or numbers stamped into the surface of the metal by its maker.
Dampen an old toothbrush with cold water, sprinkle some baking soda onto it and scrub the marks on the inside of the ring. Rinse with cold water, and the marks should be clearer to read. If the ring is new, you don't need to do this.
Examine the marks under a magnifying glass. If you're really lucky, you might see the word "sterling" or the letters "s.s." stamped on there -- if so, there's your answer! The ring is genuine sterling silver.
Are there any numbers stamped on the ring, either with or without letters next to them? If you see the number 925, .925 or any number higher than that, the ring is genuine sterling silver. The number refers to the 92.5-percent fine silver content that defines sterling silver. Any number higher than that, such as 950 or 958, shows you that the ring is of a very high quality and has a high content of fine silver.
Look for any other marks that indicate sterling silver. These include a lion symbol, which is the mark for English sterling silver; a thistle symbol, which indicates Scottish sterling silver; or an eagle, which means the ring is made of Mexican sterling silver.
If your jewelry doesn't have any hallmarks, or it does, but you are unable to decipher them, buy a silver acid test kit. The kit will contain nitric acid, instructions and a color chart. Follow the instructions carefully, scratching a hidden part of the jewelry, applying a drop of acid and examining the color that results. Compare the color to the color chart, which will tell you what color range indicates genuine silver.
If you still don't have a definite answer about the metal content of your ring, take it to a jeweler for a professional assessment.
There are ample resources on the Internet and in libraries to help you decipher hallmarks and makers' marks on jewelry. Such marks have been extensively studied, recorded and cataloged by experts. They reveal not only the metal content of jewelry, but also its country of origin, its age and sometimes the identity of the individual who made it.