It is a question I get all the time! And for good reason, there is so much cheating going on. Ebay is rampant with listings for sterling silver jewelry that are priced below even the world market price for silver. Unless these vendors have a private silver mine in their backyard, it is a dead giveaway they are cheating their customers. Most of these listings appear to come from China. The merchandise looks great, is stamped 925 but after a couple of months, it turns out it is plated when silver starts wearing off. These are the most egregious offenders.

Then there is a huge gray area of manufacturers that cut corners in less obvious but no less insidious ways. They use an actually silver alloy instead of plating, but they lower the content of silver below 92.5%, pocketing the difference. This type of silver is hard to catch for the regular retail customer. Acid tests are not easy to interpret and they damage the jewelry. As a result, these sellers usually get away with it. Especially jewelry made in India but also much silver from Bali is susceptible to this problem.

But you will be surprised to learn that not only retail consumers fall victim to unscrupulous manufacturers. Wholesale buyers get cheated themselves *all the time*. The truth is, most wholesale buyers don't have the know-how, or the budget to test all their sources. It gets very expensive to do fire assays, or x-ray tests. An x-ray gun costs upward of $15,000. Acid tests are very imprecise, fire assays are precise but destroy the sample. No wonder that many resellers prefer the approach of the 3 wise monkeys, see no evil, hear no evil, speak no evil.

And that brings me to our own situation. We have our own workshop where we control the alloy, but how do we control the quality of products that we do not manufacture ourselves? 

Well, for that I use a concept called Specific Gravity(SG). It makes use of the fact that a substance will weigh less in water, than in air. The SG is defined as the weight of 1cm3 worth of material in distilled water at 4 degrees Celsius. For silver, this weight is 10.49gram, for copper this weight is 8.93 grams. By measuring the SG of a silver/copper alloy sample, we can figure out the ratio of silver to copper!

The problem with this method is that it requires an extremely sensitive scale (to 1/10000's of a gram) to take a precise measurement. Sensitive scales are susceptible to the outside influence and require a stable lab type setup. Temperature, prep of the sample, water quality, static electricity buildup, vibration, air flow...they can all impact the measurement. Not exactly something for the faint of heart, but a perfect challenge to my inner nerd. 

With the setup pictured I can measure sterling silver content to within 1% accuracy. 

The point of the story is that it is not enough to ask your vendor whether a particular piece is sterling silver. Ask them where it comes from, what is their process, and what method do they use to verify. If the answer does not satisfy, you are well to move on.

Safe shopping!

Mark