I get asked this question a lot. And I have a few different avenues of research that I pursue when trying to “date” a particular piece.  One way is by looking at jewelry ads from old fashion magazines like this ad for Corocraft from 1957. Magazines are a wonderful way to  ”date” pieces because they will have dates on them and you can tell the approximate date of a piece by matching it to an ad.

Some vintage jewelry pieces have patents on them. This means they have a registered patent number which can be researched to determine the registration date. 

Google  has a new tool called “Google Patents” which contains a search-able data base of all US patents registered from 1790 to 2006. 

Another thing to look for would be a Copyright. In 1956 it became much more cost effective for designers to register a copyright on a design rather than go through the costly  patent process. Pieces bearing a copyright symbol indicates that it was produced in 1956 or later.

You can also look at the makers mark or signature on a piece. For example: The Schreiner Company of New York. Henry Schreiner immigrated from Bavaria Germany to the United States in 1923.  In 1939 Henry opened his own company based in New York.His daughter Terry and her husband Ambrose Albert joined the company in 1951. Henry died in 1954 and his daughter and son in law continued the business until 1975. Signed Schreiner pieces were marked with  “SCHREINER NEW YORK” in all capital letters in an oval. Some times designers did not sign their pieces. Henry Schreiner started out working for Christian Dior before opening his own company and his early pieces are not signed with his name. You can tell it was one of his designs because Henry Schreiner had a very distinctive style.

Another way to date a vintage piece of jewelry is by the style of the piece. Knowing what styles were popular over the years is very helpful.  Again  fashion magazine ads from past years are helpful as are history of costume books.