Let’s say you have a piece of vintage costume jewelry with a patent pending stamp or a patent # on the back. There are excellent web sites that are dedicated to identifying costume jewelry which was produced when jewelry designs were patented in the US. Patenting as a practice died out in the early 1950s and the heyday of patented costume jewelry was from the 1920s-1940s. The Trifari pin featured above is patented and is dated to 1953.
These sites can help you determine who manufactured and sold a piece of jewelry, the name of the designer, the date of patent, as well as other details. This information is extremely important in determining the value of a piece of vintage costume jewelry.
The following links show sites with comprehensive research resources. The sites are organized by jewelry maker and dates, along with design drawings and patent dates.
Also, if you want to see a site with loads of high-end magnificent costume jewelry that was produced during the hey-day of design check out the link below. Many of these pieces have the patent information provided.
My site: www.midcenturyjewelry.com.