• Grades of Silverplatesilver sugar bowl with silver spoon image by Alex White from Fotolia.com
  
  Silver plating means covering an object with an alloy that includes silver. Silver-plated objects are much less expensive than solid silver objects--and more durable. The value of a silver-plated object is often determined by the percentage of silver in the alloy that is used for the plating. There is no standard grading system for silver alloys, but there is a legacy of standards based on historic use.
  
  

Plating Methods

• Today. the standard method for silver-plating objects is immersing them in a bath of a solution containing silver. Electrically charging the object attracts silver to the surface. The silver grade depends on how much silver is dissolved in the bath solution and how much of the solution contains other metals--usually copper or nickel. An older method--known as Sheffield plating--wrapped the object in a metal sheet and baked it in an oven. The grade of the silver plating is determined by the grade of the silver foil. Still another method is to spray the object with a solution containing silver. This is often done in a vacuum chamber so all the silver molecules stick to the plated object. Silver plating is measured in microns and high-quality silver plating can be two or three times as thick as cheaper versions.
  
  

Numbered Grades

• There is a numbering system for silver alloys, but it is rarely used. A three-digit number signifies parts per thousand, so 500 would indicate half silver and 800 would indicate 80 percent pure silver. Using this system, "sterling silver" would be anything with 925 or higher. Another standard--also rarely used--is to record the total amount of silver used instead of the percentage. The standard for this is the "pennyweight." Twenty pennyweight is equal to one troy ounce. These two grading systems are far from universal. Usually, silver-plated items carry no indication of grade or a single word that indicates a range of grades.
  
  

Named Grades

• The most famous grade for silver is sterling: 925 or higher. This is not the highest-named grade. The highest-named grade is brittannia, which is 958. Brittannia has been the legal standard for English currency for over 400 years (and English money is refered to as sterling). Another term that indicates grade is coin silver (90% silver and 10% copper). The copper makes the coins harder and more durable. One term to watch out for is "nickel silver." It looks like silver, but contains no silver at all. It is an alloy of 65 percent copper, 28 percent nickel and 17 percent zinc. Silver-plated objects take on the grade of the silver that was used to plate them. Sometimes, the grade can be determined by consulting a catalog of "maker's marks." These marks (often a single stamped letter) are very easy to forge.