Sterling silver is not pure but has been blended with copper to form a silver composite for use in jewelry, fine housewares and collectible items. The traditional ratio of silver to copper in "Sterling Silver" is .925 to .075. " Anything below 90 percent silver is considered junk silver which may or may not be a critical term depending on the actual silver content of a given item.
Examine your silver pieces for hallmarks which indicate silver content. The numbers will provide you with the percentage of silver content and help to better determine the value of your silver by weight. A .900 stamp indicates "coin silver," a .925 stamp indicates "sterling silver" and a .999 stamp indicates "fine silver." Any stamped numbers below .900 indicate "junk silver." If you cannot find any stamps your silver may be plated and may have little or no value for precious metals buyers.
Test your silver to ensure it is real and that the stamped silver content is accurate. Place a magnet up to the silver. If it is attracted to the surface, the silver is not real. Use your metal file and scrape off a bit of the silver surface in a hidden spot. This will dig beneath the silver and expose the metal below if the object is plated and not solid. Your file should cut through silver easily but will have trouble biting into the harder steel beneath any silver plating.
Read the directions on your specific brand and type of acid test kit for silver before applying. Analyze the results and determine whether your silver is solid sterling or otherwise.
Weigh your silver using a scale with gram measurements. Round to the nearest gram and record the total. Convert your standard ounces into troy ounces using an online calculator. Troy ounces are heavier than standard ounces. While there are 16 standard ounces in a pound, there are only 12 troy ounces in a troy pound. Visit an online precious metals value calculator. Type in the total weight in troy ounces and select the purity of the silver. The program will automatically provide the approximate value based on current market rates.
Find the current market values for silver online if you prefer to do the math on your own. Use a calculator to multiply the total weight of your silver by its purity. The result is the amount of pure silver you have. Convert your results to troy ounces using an ounces to troy ounces conversion table (see Resources). Multiply the troy ounces of pure silver you have by the current market rate and you will find the approximate value.
There is a fair amount of silver plate, filled silver and other artificially weighted silver items which may provide a false value when measured as solid sterling silver. Make sure to check your silver pieces thoroughly for stamps to ensure a proper evaluation of the true silver content.
Beware of silver buyers who take large percentages off the top for every item sold. Stick with a well-established and highly-rated silver and precious metals buyer to sell your sterling silver.