Many of the silver and sterling silver jewelry items I find during my treasure hunts have hallmarks, numbers, and signatures or maker's marks stamped onto them.
Hallmarks can indicate the purity of the silver, the country/city location, the silversmith, and the approximate date made.
The number is for the purity of the silver. Silver jewelry is made of an alloy for strength as 1000 purity silver would be too soft. Sterling silver is 925 purity.The term coin silver can be 800 or 900 silver purity. (Coins have been made from 800 and 900 purity) For sterling silver you might find Ster, Sterling, .925 and/or a hallmark.
In the picture shown, you see an Eagle assay mark with the number 3. The number 3 indicates this piece is from Taxco and the ff is the artist. It is also marked Taxco Mexico 925 in a circle around the ff.
Here are the steps I take when trying to identify a vintage piece:
1) First, I will use my loupe to get the best view of the marks. Mine is a 20x power, and I am thinking of upgrading to a loupe with built in lighting. Right now I have to try to catch the light just right to see some of the smaller or more worn marks.
2) Then, after I have a good look at the marks. I will check to find them using the following books I have that specialize in silver marks:
The Little Book of Mexican Silver Trade and Hallmarks by Bille Hougart
Hallmarks of the Southwest by Barton Wright
Collectible Silver Jewelry by Fred Rezadadeh
3) And I will search on the online reference of silver marks at www.925-1000.com. This site is a huge wealth of information about silver hallmarks with pictorial examples.
4)Not all silver is marked. And if it has no marks (or the marks may be worn) and I think it might be silver I can do a quick test with a magnet. Hold the magnet close to the piece- a magnet will not stick to silver. Also, try polishing with a silver cloth and see if it leaves black on the cloth- silver will leave black on the cloth. If it passes those tests, I will take it to my local jeweler to have tested. (You can also do the nitric acid test- be careful when handling acid. Wear gloves and eye protection.)
Sometimes it takes hours to research a piece, checking the online resource and scouring through the books. It is really satisfying when I find the match.