First, you need to become familiar with the distinct styles for any time period in question.
After a short time of familiarizing yourself with the styles from different eras, you’ll naturally begin to accumulate knowledge about the materials used in necklaces during that time period, as well.
Unfortunately, you can’t always date a vintage necklace by its clasp alone.You have to take a few other factors into consideration, as well.The following two charts on clasps contain helpful information to help you with your detective work: Important Clasp Developments: Prior to 1800: s-hook, hook, pin & barrel, slide-out (tongue-in-groove) clasp, toggle Circa 1840: spring ring clasp Circa 1890: screw barrel clasp Circa 1940: box clasp Circa 1990: magnetic clasp* *(note: A patent for a magnetic clasp was applied for during the 1950s but it did not see mass-market production) Common Vintage Necklace Clasp Types by Era: Early 1900s through the 1920s: pin & barrel, screw barrel, spring ring, hook, slide-out 1930s through the 1940s: spring ring, hook, fish hook, box, screw barrel, fold-over latch, slide-out, multi-strand 1950s through the 1960s: hook, fold-over latch, fish hook, box, slide-out, multi-strand 1970 through the 1980s: spring ring, screw barrel, fold-over latch, hook, lobster, toggle, fish hook, box, slide-out, multi-strand 1990 and beyond: lobster, trigger, magnetic, toggle, fish hook, screw barrel, spring ring, slide-out, tube (modern pin & barrel), multi-strand Of course, even with the helpful charts above, you must follow a few words of caution: None of the information above will help you date a vintage necklace if someone has replaced the clasp. Clasps are susceptible to corrosion and breakage over time.This should not be surprising since clasps see more wear than the rest of a necklace due to continued opening and closure through the years.You will also become familiar with maker’s marks from certain eras if necklaces are signed.
If you are interested in vintage necklaces from a certain time period like the 1950s, it can be very informative to spend some time looking at photos and drawings of necklaces from that era online and in books.
However, they should disclose the fact that they have replaced an original clasp to all potential buyers, whether or not they found a proper substitute.
Knowledge of proper clasps for the era in which a necklace was made can be very helpful when dating a piece.
Many clasp marriages are not malicious attempts to deceive but done out of necessity.
Quite often an original clasp or a reproduction made from the proper material is just not available.
Often, it will be the incorrect type of clasp for the time period in which the necklace was made.